Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Darren Hart]

On Tue, May 24, 2016 at 09:09:38AM +0200, Pali Rohár wrote:
> On Tuesday 24 May 2016 06:48:41 Andrei Borzenkov wrote:
> > 24.05.2016 02:03, Gabriele Mazzotta пишет:
> > > On 24/05/2016 00:22, Pali Rohár wrote:

...

> > > +#ifdef CONFIG_PM_SLEEP
> > > +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> 
> I would rename this function to rbtn_clear_suspended_flag.
> 

...

> > > + /*
> > > +  * Upon resume, some BIOSes autonomously send an ACPI notification

You can drop "autonomously", it reads a bit awkwardly, and doesn't add any
information.

> > > +  * that triggers an unwanted input event. In order to ignore it,
> > > +  * we use a flag that we set at suspend and clear once we have
> > > +  * received the extra notification. Since ACPI notifications are
> > > +  * delivered asynchronously to drivers, we clear the flag from the
> > > +  * workqueue used to deliver the notifications. This should be enough
> > > +  * to guarantee that the flag is cleared only after we received the
> > > +  * extra notification, if any.
> > > +  */
> > 
> > "guarantee" is rather strong word here. We really do not know anything
> > how and when these notifications are generated by firmware, so can only
> > hope. But otherwise this explains what this patch intends to do (so that
> > even me finally understood it :)
> 
> Yes, thats better.
> 
> > > + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> > > +  rbtn_acpi_clear_flag, rbtn_data);
> > > + if (ACPI_FAILURE(status))
> > > + rbtn_data->suspended = false;
> 
> And here rbtn_clear_suspended_flag(rbtn_data) call instead direct
> assignment.
> 

I'm dropping this from the queue, and awaiting an updated version with the
requested changes (these from Pali, and the issue raised about "guarantee" being
too strong).

Thanks,

-- 
Darren Hart
Intel Open Source Technology Center

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Darren Hart]

On Tue, May 24, 2016 at 09:09:38AM +0200, Pali Rohár wrote:
> On Tuesday 24 May 2016 06:48:41 Andrei Borzenkov wrote:
> > 24.05.2016 02:03, Gabriele Mazzotta пишет:
> > > On 24/05/2016 00:22, Pali Rohár wrote:

...

> > > +#ifdef CONFIG_PM_SLEEP
> > > +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> 
> I would rename this function to rbtn_clear_suspended_flag.
> 

...

> > > + /*
> > > +  * Upon resume, some BIOSes autonomously send an ACPI notification

You can drop "autonomously", it reads a bit awkwardly, and doesn't add any
information.

> > > +  * that triggers an unwanted input event. In order to ignore it,
> > > +  * we use a flag that we set at suspend and clear once we have
> > > +  * received the extra notification. Since ACPI notifications are
> > > +  * delivered asynchronously to drivers, we clear the flag from the
> > > +  * workqueue used to deliver the notifications. This should be enough
> > > +  * to guarantee that the flag is cleared only after we received the
> > > +  * extra notification, if any.
> > > +  */
> > 
> > "guarantee" is rather strong word here. We really do not know anything
> > how and when these notifications are generated by firmware, so can only
> > hope. But otherwise this explains what this patch intends to do (so that
> > even me finally understood it :)
> 
> Yes, thats better.
> 
> > > + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> > > +  rbtn_acpi_clear_flag, rbtn_data);
> > > + if (ACPI_FAILURE(status))
> > > + rbtn_data->suspended = false;
> 
> And here rbtn_clear_suspended_flag(rbtn_data) call instead direct
> assignment.
> 

I'm dropping this from the queue, and awaiting an updated version with the
requested changes (these from Pali, and the issue raised about "guarantee" being
too strong).

Thanks,

-- 
Darren Hart
Intel Open Source Technology Center

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Pali Rohár]

On Tuesday 24 May 2016 06:48:41 Andrei Borzenkov wrote:
> 24.05.2016 02:03, Gabriele Mazzotta пишет:
> > On 24/05/2016 00:22, Pali Rohár wrote:
> >> On Tuesday 24 May 2016 00:17:15 Darren Hart wrote:
> >>> On Tue, May 24, 2016 at 12:06:03AM +0200, Pali Rohár wrote:
>  On Monday 23 May 2016 23:26:55 Darren Hart wrote:
> > I've queued this. Thanks for your patience.
> 
>  Ok, In that case I would update comments in patch to try it more
>  clear what code is doing.
> >>>
> >>> I thought I had your approval on this one Pali. Apologies if that was
> >>> not the case. Did I miss a change request from you?
> >>>
> >>> If so, please point me at it, and I'll dequeue this one and wait for
> >>> an updated one.
> >>
> >> I just wanted to review that code from somebody else and decide if 
> >> accept it or not. Because I was not sure if it is OK...
> >>
> >> But there was no objection, so patch is OK.
> >>
> >> And I pointed that patch could have better comments to describe what it 
> >> is doing as at first time I was confused.
> >>
> >> So I believe that you can update patch in your queue with new version 
> >> which just change comments in source code (without functional changes).
> >>
> > 
> > Something such as the following?
> > Feel free to reword the comments if you have something better in mind.
> > 
> > ---
> >  drivers/platform/x86/dell-rbtn.c | 56 
> > 
> >  1 file changed, 56 insertions(+)
> > 
> > diff --git a/drivers/platform/x86/dell-rbtn.c 
> > b/drivers/platform/x86/dell-rbtn.c
> > index 331d63c..e0208ba 100644
> > --- a/drivers/platform/x86/dell-rbtn.c
> > +++ b/drivers/platform/x86/dell-rbtn.c
> > @@ -28,6 +28,7 @@ struct rbtn_data {
> > enum rbtn_type type;
> > struct rfkill *rfkill;
> > struct input_dev *input_dev;
> > +   bool suspended;
> >  };
> >  
> >  
> > @@ -235,9 +236,55 @@ static const struct acpi_device_id rbtn_ids[] = {
> > { "", 0 },
> >  };
> >  
> > +#ifdef CONFIG_PM_SLEEP
> > +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)

I would rename this function to rbtn_clear_suspended_flag.

> > +{
> > +   struct rbtn_data *rbtn_data = context;
> > +
> > +   rbtn_data->suspended = false;
> > +}
> > +
> > +static int rbtn_suspend(struct device *dev)
> > +{
> > +   struct acpi_device *device = to_acpi_device(dev);
> > +   struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > +
> > +   rbtn_data->suspended = true;
> > +
> > +   return 0;
> > +}
> > +
> > +static int rbtn_resume(struct device *dev)
> > +{
> > +   struct acpi_device *device = to_acpi_device(dev);
> > +   struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > +   acpi_status status;
> > +
> > +   /*
> > +* Upon resume, some BIOSes autonomously send an ACPI notification
> > +* that triggers an unwanted input event. In order to ignore it,
> > +* we use a flag that we set at suspend and clear once we have
> > +* received the extra notification. Since ACPI notifications are
> > +* delivered asynchronously to drivers, we clear the flag from the
> > +* workqueue used to deliver the notifications. This should be enough
> > +* to guarantee that the flag is cleared only after we received the
> > +* extra notification, if any.
> > +*/
> 
> "guarantee" is rather strong word here. We really do not know anything
> how and when these notifications are generated by firmware, so can only
> hope. But otherwise this explains what this patch intends to do (so that
> even me finally understood it :)

Yes, thats better.

> > +   status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> > +rbtn_acpi_clear_flag, rbtn_data);
> > +   if (ACPI_FAILURE(status))
> > +   rbtn_data->suspended = false;

And here rbtn_clear_suspended_flag(rbtn_data) call instead direct
assignment.

> > +
> > +   return 0;
> > +}
> > +#endif
> > +
> > +static SIMPLE_DEV_PM_OPS(rbtn_pm_ops, rbtn_suspend, rbtn_resume);
> > +
> >  static struct acpi_driver rbtn_driver = {
> > .name = "dell-rbtn",
> > .ids = rbtn_ids,
> > +   .drv.pm = _pm_ops,
> > .ops = {
> > .add = rbtn_add,
> > .remove = rbtn_remove,
> > @@ -399,6 +446,15 @@ static void rbtn_notify(struct acpi_device *device, 
> > u32 event)
> >  {
> > struct rbtn_data *rbtn_data = device->driver_data;
> >  
> > +   /*
> > +* Some BIOSes send autonomously a notification at resume.
> > +* Ignore it to prevent unwanted input events.
> > +*/
> > +   if (rbtn_data->suspended) {
> > +   dev_dbg(>dev, "ACPI notification ignored\n");
> > +   return;
> > +   }
> > +
> > if (event != 0x80) {
> > dev_info(>dev, "Received unknown event (0x%x)\n",
> >  event);
> > 
> 

-- 
Pali Rohár
pali.ro...@gmail.com

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Pali Rohár]

On Tuesday 24 May 2016 06:48:41 Andrei Borzenkov wrote:
> 24.05.2016 02:03, Gabriele Mazzotta пишет:
> > On 24/05/2016 00:22, Pali Rohár wrote:
> >> On Tuesday 24 May 2016 00:17:15 Darren Hart wrote:
> >>> On Tue, May 24, 2016 at 12:06:03AM +0200, Pali Rohár wrote:
>  On Monday 23 May 2016 23:26:55 Darren Hart wrote:
> > I've queued this. Thanks for your patience.
> 
>  Ok, In that case I would update comments in patch to try it more
>  clear what code is doing.
> >>>
> >>> I thought I had your approval on this one Pali. Apologies if that was
> >>> not the case. Did I miss a change request from you?
> >>>
> >>> If so, please point me at it, and I'll dequeue this one and wait for
> >>> an updated one.
> >>
> >> I just wanted to review that code from somebody else and decide if 
> >> accept it or not. Because I was not sure if it is OK...
> >>
> >> But there was no objection, so patch is OK.
> >>
> >> And I pointed that patch could have better comments to describe what it 
> >> is doing as at first time I was confused.
> >>
> >> So I believe that you can update patch in your queue with new version 
> >> which just change comments in source code (without functional changes).
> >>
> > 
> > Something such as the following?
> > Feel free to reword the comments if you have something better in mind.
> > 
> > ---
> >  drivers/platform/x86/dell-rbtn.c | 56 
> > 
> >  1 file changed, 56 insertions(+)
> > 
> > diff --git a/drivers/platform/x86/dell-rbtn.c 
> > b/drivers/platform/x86/dell-rbtn.c
> > index 331d63c..e0208ba 100644
> > --- a/drivers/platform/x86/dell-rbtn.c
> > +++ b/drivers/platform/x86/dell-rbtn.c
> > @@ -28,6 +28,7 @@ struct rbtn_data {
> > enum rbtn_type type;
> > struct rfkill *rfkill;
> > struct input_dev *input_dev;
> > +   bool suspended;
> >  };
> >  
> >  
> > @@ -235,9 +236,55 @@ static const struct acpi_device_id rbtn_ids[] = {
> > { "", 0 },
> >  };
> >  
> > +#ifdef CONFIG_PM_SLEEP
> > +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)

I would rename this function to rbtn_clear_suspended_flag.

> > +{
> > +   struct rbtn_data *rbtn_data = context;
> > +
> > +   rbtn_data->suspended = false;
> > +}
> > +
> > +static int rbtn_suspend(struct device *dev)
> > +{
> > +   struct acpi_device *device = to_acpi_device(dev);
> > +   struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > +
> > +   rbtn_data->suspended = true;
> > +
> > +   return 0;
> > +}
> > +
> > +static int rbtn_resume(struct device *dev)
> > +{
> > +   struct acpi_device *device = to_acpi_device(dev);
> > +   struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > +   acpi_status status;
> > +
> > +   /*
> > +* Upon resume, some BIOSes autonomously send an ACPI notification
> > +* that triggers an unwanted input event. In order to ignore it,
> > +* we use a flag that we set at suspend and clear once we have
> > +* received the extra notification. Since ACPI notifications are
> > +* delivered asynchronously to drivers, we clear the flag from the
> > +* workqueue used to deliver the notifications. This should be enough
> > +* to guarantee that the flag is cleared only after we received the
> > +* extra notification, if any.
> > +*/
> 
> "guarantee" is rather strong word here. We really do not know anything
> how and when these notifications are generated by firmware, so can only
> hope. But otherwise this explains what this patch intends to do (so that
> even me finally understood it :)

Yes, thats better.

> > +   status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> > +rbtn_acpi_clear_flag, rbtn_data);
> > +   if (ACPI_FAILURE(status))
> > +   rbtn_data->suspended = false;

And here rbtn_clear_suspended_flag(rbtn_data) call instead direct
assignment.

> > +
> > +   return 0;
> > +}
> > +#endif
> > +
> > +static SIMPLE_DEV_PM_OPS(rbtn_pm_ops, rbtn_suspend, rbtn_resume);
> > +
> >  static struct acpi_driver rbtn_driver = {
> > .name = "dell-rbtn",
> > .ids = rbtn_ids,
> > +   .drv.pm = _pm_ops,
> > .ops = {
> > .add = rbtn_add,
> > .remove = rbtn_remove,
> > @@ -399,6 +446,15 @@ static void rbtn_notify(struct acpi_device *device, 
> > u32 event)
> >  {
> > struct rbtn_data *rbtn_data = device->driver_data;
> >  
> > +   /*
> > +* Some BIOSes send autonomously a notification at resume.
> > +* Ignore it to prevent unwanted input events.
> > +*/
> > +   if (rbtn_data->suspended) {
> > +   dev_dbg(>dev, "ACPI notification ignored\n");
> > +   return;
> > +   }
> > +
> > if (event != 0x80) {
> > dev_info(>dev, "Received unknown event (0x%x)\n",
> >  event);
> > 
> 

-- 
Pali Rohár
pali.ro...@gmail.com

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Andrei Borzenkov]

24.05.2016 02:03, Gabriele Mazzotta пишет:
> On 24/05/2016 00:22, Pali Rohár wrote:
>> On Tuesday 24 May 2016 00:17:15 Darren Hart wrote:
>>> On Tue, May 24, 2016 at 12:06:03AM +0200, Pali Rohár wrote:
 On Monday 23 May 2016 23:26:55 Darren Hart wrote:
> I've queued this. Thanks for your patience.

 Ok, In that case I would update comments in patch to try it more
 clear what code is doing.
>>>
>>> I thought I had your approval on this one Pali. Apologies if that was
>>> not the case. Did I miss a change request from you?
>>>
>>> If so, please point me at it, and I'll dequeue this one and wait for
>>> an updated one.
>>
>> I just wanted to review that code from somebody else and decide if 
>> accept it or not. Because I was not sure if it is OK...
>>
>> But there was no objection, so patch is OK.
>>
>> And I pointed that patch could have better comments to describe what it 
>> is doing as at first time I was confused.
>>
>> So I believe that you can update patch in your queue with new version 
>> which just change comments in source code (without functional changes).
>>
> 
> Something such as the following?
> Feel free to reword the comments if you have something better in mind.
> 
> ---
>  drivers/platform/x86/dell-rbtn.c | 56 
> 
>  1 file changed, 56 insertions(+)
> 
> diff --git a/drivers/platform/x86/dell-rbtn.c 
> b/drivers/platform/x86/dell-rbtn.c
> index 331d63c..e0208ba 100644
> --- a/drivers/platform/x86/dell-rbtn.c
> +++ b/drivers/platform/x86/dell-rbtn.c
> @@ -28,6 +28,7 @@ struct rbtn_data {
>   enum rbtn_type type;
>   struct rfkill *rfkill;
>   struct input_dev *input_dev;
> + bool suspended;
>  };
>  
>  
> @@ -235,9 +236,55 @@ static const struct acpi_device_id rbtn_ids[] = {
>   { "", 0 },
>  };
>  
> +#ifdef CONFIG_PM_SLEEP
> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> +{
> + struct rbtn_data *rbtn_data = context;
> +
> + rbtn_data->suspended = false;
> +}
> +
> +static int rbtn_suspend(struct device *dev)
> +{
> + struct acpi_device *device = to_acpi_device(dev);
> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> +
> + rbtn_data->suspended = true;
> +
> + return 0;
> +}
> +
> +static int rbtn_resume(struct device *dev)
> +{
> + struct acpi_device *device = to_acpi_device(dev);
> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> + acpi_status status;
> +
> + /*
> +  * Upon resume, some BIOSes autonomously send an ACPI notification
> +  * that triggers an unwanted input event. In order to ignore it,
> +  * we use a flag that we set at suspend and clear once we have
> +  * received the extra notification. Since ACPI notifications are
> +  * delivered asynchronously to drivers, we clear the flag from the
> +  * workqueue used to deliver the notifications. This should be enough
> +  * to guarantee that the flag is cleared only after we received the
> +  * extra notification, if any.
> +  */

"guarantee" is rather strong word here. We really do not know anything
how and when these notifications are generated by firmware, so can only
hope. But otherwise this explains what this patch intends to do (so that
even me finally understood it :)

> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> +  rbtn_acpi_clear_flag, rbtn_data);
> + if (ACPI_FAILURE(status))
> + rbtn_data->suspended = false;
> +
> + return 0;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(rbtn_pm_ops, rbtn_suspend, rbtn_resume);
> +
>  static struct acpi_driver rbtn_driver = {
>   .name = "dell-rbtn",
>   .ids = rbtn_ids,
> + .drv.pm = _pm_ops,
>   .ops = {
>   .add = rbtn_add,
>   .remove = rbtn_remove,
> @@ -399,6 +446,15 @@ static void rbtn_notify(struct acpi_device *device, u32 
> event)
>  {
>   struct rbtn_data *rbtn_data = device->driver_data;
>  
> + /*
> +  * Some BIOSes send autonomously a notification at resume.
> +  * Ignore it to prevent unwanted input events.
> +  */
> + if (rbtn_data->suspended) {
> + dev_dbg(>dev, "ACPI notification ignored\n");
> + return;
> + }
> +
>   if (event != 0x80) {
>   dev_info(>dev, "Received unknown event (0x%x)\n",
>event);
> 

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Andrei Borzenkov]

24.05.2016 02:03, Gabriele Mazzotta пишет:
> On 24/05/2016 00:22, Pali Rohár wrote:
>> On Tuesday 24 May 2016 00:17:15 Darren Hart wrote:
>>> On Tue, May 24, 2016 at 12:06:03AM +0200, Pali Rohár wrote:
 On Monday 23 May 2016 23:26:55 Darren Hart wrote:
> I've queued this. Thanks for your patience.

 Ok, In that case I would update comments in patch to try it more
 clear what code is doing.
>>>
>>> I thought I had your approval on this one Pali. Apologies if that was
>>> not the case. Did I miss a change request from you?
>>>
>>> If so, please point me at it, and I'll dequeue this one and wait for
>>> an updated one.
>>
>> I just wanted to review that code from somebody else and decide if 
>> accept it or not. Because I was not sure if it is OK...
>>
>> But there was no objection, so patch is OK.
>>
>> And I pointed that patch could have better comments to describe what it 
>> is doing as at first time I was confused.
>>
>> So I believe that you can update patch in your queue with new version 
>> which just change comments in source code (without functional changes).
>>
> 
> Something such as the following?
> Feel free to reword the comments if you have something better in mind.
> 
> ---
>  drivers/platform/x86/dell-rbtn.c | 56 
> 
>  1 file changed, 56 insertions(+)
> 
> diff --git a/drivers/platform/x86/dell-rbtn.c 
> b/drivers/platform/x86/dell-rbtn.c
> index 331d63c..e0208ba 100644
> --- a/drivers/platform/x86/dell-rbtn.c
> +++ b/drivers/platform/x86/dell-rbtn.c
> @@ -28,6 +28,7 @@ struct rbtn_data {
>   enum rbtn_type type;
>   struct rfkill *rfkill;
>   struct input_dev *input_dev;
> + bool suspended;
>  };
>  
>  
> @@ -235,9 +236,55 @@ static const struct acpi_device_id rbtn_ids[] = {
>   { "", 0 },
>  };
>  
> +#ifdef CONFIG_PM_SLEEP
> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> +{
> + struct rbtn_data *rbtn_data = context;
> +
> + rbtn_data->suspended = false;
> +}
> +
> +static int rbtn_suspend(struct device *dev)
> +{
> + struct acpi_device *device = to_acpi_device(dev);
> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> +
> + rbtn_data->suspended = true;
> +
> + return 0;
> +}
> +
> +static int rbtn_resume(struct device *dev)
> +{
> + struct acpi_device *device = to_acpi_device(dev);
> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> + acpi_status status;
> +
> + /*
> +  * Upon resume, some BIOSes autonomously send an ACPI notification
> +  * that triggers an unwanted input event. In order to ignore it,
> +  * we use a flag that we set at suspend and clear once we have
> +  * received the extra notification. Since ACPI notifications are
> +  * delivered asynchronously to drivers, we clear the flag from the
> +  * workqueue used to deliver the notifications. This should be enough
> +  * to guarantee that the flag is cleared only after we received the
> +  * extra notification, if any.
> +  */

"guarantee" is rather strong word here. We really do not know anything
how and when these notifications are generated by firmware, so can only
hope. But otherwise this explains what this patch intends to do (so that
even me finally understood it :)

> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> +  rbtn_acpi_clear_flag, rbtn_data);
> + if (ACPI_FAILURE(status))
> + rbtn_data->suspended = false;
> +
> + return 0;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(rbtn_pm_ops, rbtn_suspend, rbtn_resume);
> +
>  static struct acpi_driver rbtn_driver = {
>   .name = "dell-rbtn",
>   .ids = rbtn_ids,
> + .drv.pm = _pm_ops,
>   .ops = {
>   .add = rbtn_add,
>   .remove = rbtn_remove,
> @@ -399,6 +446,15 @@ static void rbtn_notify(struct acpi_device *device, u32 
> event)
>  {
>   struct rbtn_data *rbtn_data = device->driver_data;
>  
> + /*
> +  * Some BIOSes send autonomously a notification at resume.
> +  * Ignore it to prevent unwanted input events.
> +  */
> + if (rbtn_data->suspended) {
> + dev_dbg(>dev, "ACPI notification ignored\n");
> + return;
> + }
> +
>   if (event != 0x80) {
>   dev_info(>dev, "Received unknown event (0x%x)\n",
>event);
> 

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Gabriele Mazzotta]

On 24/05/2016 00:22, Pali Rohár wrote:
> On Tuesday 24 May 2016 00:17:15 Darren Hart wrote:
>> On Tue, May 24, 2016 at 12:06:03AM +0200, Pali Rohár wrote:
>>> On Monday 23 May 2016 23:26:55 Darren Hart wrote:
 I've queued this. Thanks for your patience.
>>>
>>> Ok, In that case I would update comments in patch to try it more
>>> clear what code is doing.
>>
>> I thought I had your approval on this one Pali. Apologies if that was
>> not the case. Did I miss a change request from you?
>>
>> If so, please point me at it, and I'll dequeue this one and wait for
>> an updated one.
> 
> I just wanted to review that code from somebody else and decide if 
> accept it or not. Because I was not sure if it is OK...
> 
> But there was no objection, so patch is OK.
> 
> And I pointed that patch could have better comments to describe what it 
> is doing as at first time I was confused.
> 
> So I believe that you can update patch in your queue with new version 
> which just change comments in source code (without functional changes).
> 

Something such as the following?
Feel free to reword the comments if you have something better in mind.

---
 drivers/platform/x86/dell-rbtn.c | 56 
 1 file changed, 56 insertions(+)

diff --git a/drivers/platform/x86/dell-rbtn.c b/drivers/platform/x86/dell-rbtn.c
index 331d63c..e0208ba 100644
--- a/drivers/platform/x86/dell-rbtn.c
+++ b/drivers/platform/x86/dell-rbtn.c
@@ -28,6 +28,7 @@ struct rbtn_data {
enum rbtn_type type;
struct rfkill *rfkill;
struct input_dev *input_dev;
+   bool suspended;
 };
 
 
@@ -235,9 +236,55 @@ static const struct acpi_device_id rbtn_ids[] = {
{ "", 0 },
 };
 
+#ifdef CONFIG_PM_SLEEP
+static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
+{
+   struct rbtn_data *rbtn_data = context;
+
+   rbtn_data->suspended = false;
+}
+
+static int rbtn_suspend(struct device *dev)
+{
+   struct acpi_device *device = to_acpi_device(dev);
+   struct rbtn_data *rbtn_data = acpi_driver_data(device);
+
+   rbtn_data->suspended = true;
+
+   return 0;
+}
+
+static int rbtn_resume(struct device *dev)
+{
+   struct acpi_device *device = to_acpi_device(dev);
+   struct rbtn_data *rbtn_data = acpi_driver_data(device);
+   acpi_status status;
+
+   /*
+* Upon resume, some BIOSes autonomously send an ACPI notification
+* that triggers an unwanted input event. In order to ignore it,
+* we use a flag that we set at suspend and clear once we have
+* received the extra notification. Since ACPI notifications are
+* delivered asynchronously to drivers, we clear the flag from the
+* workqueue used to deliver the notifications. This should be enough
+* to guarantee that the flag is cleared only after we received the
+* extra notification, if any.
+*/
+   status = acpi_os_execute(OSL_NOTIFY_HANDLER,
+rbtn_acpi_clear_flag, rbtn_data);
+   if (ACPI_FAILURE(status))
+   rbtn_data->suspended = false;
+
+   return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(rbtn_pm_ops, rbtn_suspend, rbtn_resume);
+
 static struct acpi_driver rbtn_driver = {
.name = "dell-rbtn",
.ids = rbtn_ids,
+   .drv.pm = _pm_ops,
.ops = {
.add = rbtn_add,
.remove = rbtn_remove,
@@ -399,6 +446,15 @@ static void rbtn_notify(struct acpi_device *device, u32 
event)
 {
struct rbtn_data *rbtn_data = device->driver_data;
 
+   /*
+* Some BIOSes send autonomously a notification at resume.
+* Ignore it to prevent unwanted input events.
+*/
+   if (rbtn_data->suspended) {
+   dev_dbg(>dev, "ACPI notification ignored\n");
+   return;
+   }
+
if (event != 0x80) {
dev_info(>dev, "Received unknown event (0x%x)\n",
 event);
-- 
2.8.1

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Gabriele Mazzotta]

On 24/05/2016 00:22, Pali Rohár wrote:
> On Tuesday 24 May 2016 00:17:15 Darren Hart wrote:
>> On Tue, May 24, 2016 at 12:06:03AM +0200, Pali Rohár wrote:
>>> On Monday 23 May 2016 23:26:55 Darren Hart wrote:
 I've queued this. Thanks for your patience.
>>>
>>> Ok, In that case I would update comments in patch to try it more
>>> clear what code is doing.
>>
>> I thought I had your approval on this one Pali. Apologies if that was
>> not the case. Did I miss a change request from you?
>>
>> If so, please point me at it, and I'll dequeue this one and wait for
>> an updated one.
> 
> I just wanted to review that code from somebody else and decide if 
> accept it or not. Because I was not sure if it is OK...
> 
> But there was no objection, so patch is OK.
> 
> And I pointed that patch could have better comments to describe what it 
> is doing as at first time I was confused.
> 
> So I believe that you can update patch in your queue with new version 
> which just change comments in source code (without functional changes).
> 

Something such as the following?
Feel free to reword the comments if you have something better in mind.

---
 drivers/platform/x86/dell-rbtn.c | 56 
 1 file changed, 56 insertions(+)

diff --git a/drivers/platform/x86/dell-rbtn.c b/drivers/platform/x86/dell-rbtn.c
index 331d63c..e0208ba 100644
--- a/drivers/platform/x86/dell-rbtn.c
+++ b/drivers/platform/x86/dell-rbtn.c
@@ -28,6 +28,7 @@ struct rbtn_data {
enum rbtn_type type;
struct rfkill *rfkill;
struct input_dev *input_dev;
+   bool suspended;
 };
 
 
@@ -235,9 +236,55 @@ static const struct acpi_device_id rbtn_ids[] = {
{ "", 0 },
 };
 
+#ifdef CONFIG_PM_SLEEP
+static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
+{
+   struct rbtn_data *rbtn_data = context;
+
+   rbtn_data->suspended = false;
+}
+
+static int rbtn_suspend(struct device *dev)
+{
+   struct acpi_device *device = to_acpi_device(dev);
+   struct rbtn_data *rbtn_data = acpi_driver_data(device);
+
+   rbtn_data->suspended = true;
+
+   return 0;
+}
+
+static int rbtn_resume(struct device *dev)
+{
+   struct acpi_device *device = to_acpi_device(dev);
+   struct rbtn_data *rbtn_data = acpi_driver_data(device);
+   acpi_status status;
+
+   /*
+* Upon resume, some BIOSes autonomously send an ACPI notification
+* that triggers an unwanted input event. In order to ignore it,
+* we use a flag that we set at suspend and clear once we have
+* received the extra notification. Since ACPI notifications are
+* delivered asynchronously to drivers, we clear the flag from the
+* workqueue used to deliver the notifications. This should be enough
+* to guarantee that the flag is cleared only after we received the
+* extra notification, if any.
+*/
+   status = acpi_os_execute(OSL_NOTIFY_HANDLER,
+rbtn_acpi_clear_flag, rbtn_data);
+   if (ACPI_FAILURE(status))
+   rbtn_data->suspended = false;
+
+   return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(rbtn_pm_ops, rbtn_suspend, rbtn_resume);
+
 static struct acpi_driver rbtn_driver = {
.name = "dell-rbtn",
.ids = rbtn_ids,
+   .drv.pm = _pm_ops,
.ops = {
.add = rbtn_add,
.remove = rbtn_remove,
@@ -399,6 +446,15 @@ static void rbtn_notify(struct acpi_device *device, u32 
event)
 {
struct rbtn_data *rbtn_data = device->driver_data;
 
+   /*
+* Some BIOSes send autonomously a notification at resume.
+* Ignore it to prevent unwanted input events.
+*/
+   if (rbtn_data->suspended) {
+   dev_dbg(>dev, "ACPI notification ignored\n");
+   return;
+   }
+
if (event != 0x80) {
dev_info(>dev, "Received unknown event (0x%x)\n",
 event);
-- 
2.8.1

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Pali Rohár]

On Tuesday 24 May 2016 00:17:15 Darren Hart wrote:
> On Tue, May 24, 2016 at 12:06:03AM +0200, Pali Rohár wrote:
> > On Monday 23 May 2016 23:26:55 Darren Hart wrote:
> > > I've queued this. Thanks for your patience.
> > 
> > Ok, In that case I would update comments in patch to try it more
> > clear what code is doing.
> 
> I thought I had your approval on this one Pali. Apologies if that was
> not the case. Did I miss a change request from you?
> 
> If so, please point me at it, and I'll dequeue this one and wait for
> an updated one.

I just wanted to review that code from somebody else and decide if 
accept it or not. Because I was not sure if it is OK...

But there was no objection, so patch is OK.

And I pointed that patch could have better comments to describe what it 
is doing as at first time I was confused.

So I believe that you can update patch in your queue with new version 
which just change comments in source code (without functional changes).

-- 
Pali Rohár
pali.ro...@gmail.com


signature.asc
Description: This is a digitally signed message part.

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Pali Rohár]

On Tuesday 24 May 2016 00:17:15 Darren Hart wrote:
> On Tue, May 24, 2016 at 12:06:03AM +0200, Pali Rohár wrote:
> > On Monday 23 May 2016 23:26:55 Darren Hart wrote:
> > > I've queued this. Thanks for your patience.
> > 
> > Ok, In that case I would update comments in patch to try it more
> > clear what code is doing.
> 
> I thought I had your approval on this one Pali. Apologies if that was
> not the case. Did I miss a change request from you?
> 
> If so, please point me at it, and I'll dequeue this one and wait for
> an updated one.

I just wanted to review that code from somebody else and decide if 
accept it or not. Because I was not sure if it is OK...

But there was no objection, so patch is OK.

And I pointed that patch could have better comments to describe what it 
is doing as at first time I was confused.

So I believe that you can update patch in your queue with new version 
which just change comments in source code (without functional changes).

-- 
Pali Rohár
pali.ro...@gmail.com


signature.asc
Description: This is a digitally signed message part.

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Darren Hart]

On Tue, May 24, 2016 at 12:06:03AM +0200, Pali Rohár wrote:
> On Monday 23 May 2016 23:26:55 Darren Hart wrote:
> > I've queued this. Thanks for your patience.
> 
> Ok, In that case I would update comments in patch to try it more clear 
> what code is doing.

I thought I had your approval on this one Pali. Apologies if that was not the
case. Did I miss a change request from you?

If so, please point me at it, and I'll dequeue this one and wait for an updated
one.


-- 
Darren Hart
Intel Open Source Technology Center

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Darren Hart]

On Tue, May 24, 2016 at 12:06:03AM +0200, Pali Rohár wrote:
> On Monday 23 May 2016 23:26:55 Darren Hart wrote:
> > I've queued this. Thanks for your patience.
> 
> Ok, In that case I would update comments in patch to try it more clear 
> what code is doing.

I thought I had your approval on this one Pali. Apologies if that was not the
case. Did I miss a change request from you?

If so, please point me at it, and I'll dequeue this one and wait for an updated
one.


-- 
Darren Hart
Intel Open Source Technology Center

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Pali Rohár]

On Monday 23 May 2016 23:26:55 Darren Hart wrote:
> I've queued this. Thanks for your patience.

Ok, In that case I would update comments in patch to try it more clear 
what code is doing.

-- 
Pali Rohár
pali.ro...@gmail.com


signature.asc
Description: This is a digitally signed message part.

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Pali Rohár]

On Monday 23 May 2016 23:26:55 Darren Hart wrote:
> I've queued this. Thanks for your patience.

Ok, In that case I would update comments in patch to try it more clear 
what code is doing.

-- 
Pali Rohár
pali.ro...@gmail.com


signature.asc
Description: This is a digitally signed message part.

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Darren Hart]

On Thu, May 19, 2016 at 03:30:32PM +0200, Pali Rohár wrote:
> On Monday 25 April 2016 22:06:11 Gabriele Mazzotta wrote:
> > 2016-04-18 14:35 GMT+02:00 Pali Rohár :
> > > On Tuesday 29 March 2016 15:11:35 Rafael J. Wysocki wrote:
> > >> On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote:
> > >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> > >> > > 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> > >> > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> > >> > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> > >> > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> > >> > > >> >> +#ifdef CONFIG_PM_SLEEP
> > >> > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void 
> > >> > > >> >> *context)
> > >> > > >> >> +{
> > >> > > >> >> + struct rbtn_data *rbtn_data = context;
> > >> > > >> >> +
> > >> > > >> >> + rbtn_data->suspended = false;
> > >> > > >> >> +}
> > >> > > >> >> +
> > >> > > >> >> +static int rbtn_suspend(struct device *dev)
> > >> > > >> >> +{
> > >> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
> > >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > >> > > >> >> +
> > >> > > >> >> + rbtn_data->suspended = true;
> > >> > > >> >> +
> > >> > > >> >> + return 0;
> > >> > > >> >> +}
> > >> > > >> >> +
> > >> > > >> >> +static int rbtn_resume(struct device *dev)
> > >> > > >> >> +{
> > >> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
> > >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > >> > > >> >> + acpi_status status;
> > >> > > >> >> +
> > >> > > >> >> + /*
> > >> > > >> >> +  * Clear the flag only after we received the extra
> > >> > > >> >> +  * ACPI notification.
> > >> > > >> >> +  */
> > >> > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> > >> > > >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> > >> > > >> >> + if (ACPI_FAILURE(status))
> > >> > > >> >> + rbtn_data->suspended = false;
> > >> > > >> >
> > >> > > >> > I case when acpi_os_execute success it calls 
> > >> > > >> > rbtn_acpi_clear_flag,
> > >> > > >> > right? And that will set suspended to false. When 
> > >> > > >> > acpi_os_execute fails,
> > >> > > >> > then it set suspended too to false... Then whole 
> > >> > > >> > acpi_os_execute doing
> > >> > > >> > just "barrier" after which suspended flag can be set to false. 
> > >> > > >> > So I
> > >> > > >> > think rbtn_acpi_clear_flag function is not needed here.
> > >> > > >> >
> > >> > > >> > Cannot you pass NULL or empty function pointer as callback? Or 
> > >> > > >> > what was
> > >> > > >> > reason to do that flag clearing at "two places"?
> > >> > > >>
> > >> > > >> acpi_os_execute doesn't wait for the callback to be executed, so
> > >> > > >> I can't clear the flag from rbtn_resume.
> > >> > > >
> > >> > > > acpi_os_execute calls callback asynchronously later? Or what 
> > >> > > > exactly do it?
> > >> > >
> > >> > > In this case, it adds the callback to the kacpi_notify_wq workqueue
> > >> > > for deferred execution.
> > >> >
> > >> > +Rafael for context/advice on the use of acpi_os_execute here.
> > >> >
> > >> > This is true, but a quick scan through that call path doesn't tell me 
> > >> > why we
> > >> > would need to call it here instead of just setting 
> > >> > rbtn_data->suspended = false.
> > >> > The comment suggests waiting for the event, but is that what this is 
> > >> > doing? It
> > >> > appears to me to be immediately scheduling the function to a work 
> > >> > queue, not
> > >> > waiting for the event notifier.
> > >>
> > >> I think this is supposed to work as a barrier.  That is, it will only 
> > >> run after
> > >> all events in the queue have been processed.
> > >>
> > >> I'm not sure if that's necessary, though.
> > >>
> > >> Thanks,
> > >> Rafael
> > >>
> > >
> > > Darren, Gabriele, what is state of this patch? Bug is not still fixed,
> > > right?
> > 
> > Yes, the bug is still there and this patch fixes it.
> > 
> > Just to make it clear, we need the barrier. Andrei could reproduce
> > the bug without it [1], but not with it, as he confirmed in this
> > thread [2].
> > 
> > [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001
> > [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8937
> 
> Ok, so it means that somebody (who understand ACPI) should review code
> and accept it or show what is needed to fix. Plus maybe adds more
> comments how that "barrier" works as I was first confused...
> 
> Darren, Rafael, can you do review of this patch?
> 

Pali and Gabriele have responded to all questions raised. I have some
reservations that this solution is still a bit racy, but it does fix the problem
for the affected users.

I've queued this. Thanks for your patience.

-- 
Darren Hart
Intel Open Source Technology 

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Darren Hart]

On Thu, May 19, 2016 at 03:30:32PM +0200, Pali Rohár wrote:
> On Monday 25 April 2016 22:06:11 Gabriele Mazzotta wrote:
> > 2016-04-18 14:35 GMT+02:00 Pali Rohár :
> > > On Tuesday 29 March 2016 15:11:35 Rafael J. Wysocki wrote:
> > >> On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote:
> > >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> > >> > > 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> > >> > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> > >> > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> > >> > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> > >> > > >> >> +#ifdef CONFIG_PM_SLEEP
> > >> > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void 
> > >> > > >> >> *context)
> > >> > > >> >> +{
> > >> > > >> >> + struct rbtn_data *rbtn_data = context;
> > >> > > >> >> +
> > >> > > >> >> + rbtn_data->suspended = false;
> > >> > > >> >> +}
> > >> > > >> >> +
> > >> > > >> >> +static int rbtn_suspend(struct device *dev)
> > >> > > >> >> +{
> > >> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
> > >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > >> > > >> >> +
> > >> > > >> >> + rbtn_data->suspended = true;
> > >> > > >> >> +
> > >> > > >> >> + return 0;
> > >> > > >> >> +}
> > >> > > >> >> +
> > >> > > >> >> +static int rbtn_resume(struct device *dev)
> > >> > > >> >> +{
> > >> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
> > >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > >> > > >> >> + acpi_status status;
> > >> > > >> >> +
> > >> > > >> >> + /*
> > >> > > >> >> +  * Clear the flag only after we received the extra
> > >> > > >> >> +  * ACPI notification.
> > >> > > >> >> +  */
> > >> > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> > >> > > >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> > >> > > >> >> + if (ACPI_FAILURE(status))
> > >> > > >> >> + rbtn_data->suspended = false;
> > >> > > >> >
> > >> > > >> > I case when acpi_os_execute success it calls 
> > >> > > >> > rbtn_acpi_clear_flag,
> > >> > > >> > right? And that will set suspended to false. When 
> > >> > > >> > acpi_os_execute fails,
> > >> > > >> > then it set suspended too to false... Then whole 
> > >> > > >> > acpi_os_execute doing
> > >> > > >> > just "barrier" after which suspended flag can be set to false. 
> > >> > > >> > So I
> > >> > > >> > think rbtn_acpi_clear_flag function is not needed here.
> > >> > > >> >
> > >> > > >> > Cannot you pass NULL or empty function pointer as callback? Or 
> > >> > > >> > what was
> > >> > > >> > reason to do that flag clearing at "two places"?
> > >> > > >>
> > >> > > >> acpi_os_execute doesn't wait for the callback to be executed, so
> > >> > > >> I can't clear the flag from rbtn_resume.
> > >> > > >
> > >> > > > acpi_os_execute calls callback asynchronously later? Or what 
> > >> > > > exactly do it?
> > >> > >
> > >> > > In this case, it adds the callback to the kacpi_notify_wq workqueue
> > >> > > for deferred execution.
> > >> >
> > >> > +Rafael for context/advice on the use of acpi_os_execute here.
> > >> >
> > >> > This is true, but a quick scan through that call path doesn't tell me 
> > >> > why we
> > >> > would need to call it here instead of just setting 
> > >> > rbtn_data->suspended = false.
> > >> > The comment suggests waiting for the event, but is that what this is 
> > >> > doing? It
> > >> > appears to me to be immediately scheduling the function to a work 
> > >> > queue, not
> > >> > waiting for the event notifier.
> > >>
> > >> I think this is supposed to work as a barrier.  That is, it will only 
> > >> run after
> > >> all events in the queue have been processed.
> > >>
> > >> I'm not sure if that's necessary, though.
> > >>
> > >> Thanks,
> > >> Rafael
> > >>
> > >
> > > Darren, Gabriele, what is state of this patch? Bug is not still fixed,
> > > right?
> > 
> > Yes, the bug is still there and this patch fixes it.
> > 
> > Just to make it clear, we need the barrier. Andrei could reproduce
> > the bug without it [1], but not with it, as he confirmed in this
> > thread [2].
> > 
> > [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001
> > [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8937
> 
> Ok, so it means that somebody (who understand ACPI) should review code
> and accept it or show what is needed to fix. Plus maybe adds more
> comments how that "barrier" works as I was first confused...
> 
> Darren, Rafael, can you do review of this patch?
> 

Pali and Gabriele have responded to all questions raised. I have some
reservations that this solution is still a bit racy, but it does fix the problem
for the affected users.

I've queued this. Thanks for your patience.

-- 
Darren Hart
Intel Open Source Technology Center

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Darren Hart]

On Thu, May 19, 2016 at 03:30:32PM +0200, Pali Rohár wrote:
> On Monday 25 April 2016 22:06:11 Gabriele Mazzotta wrote:
> > 2016-04-18 14:35 GMT+02:00 Pali Rohár :
> > > On Tuesday 29 March 2016 15:11:35 Rafael J. Wysocki wrote:
> > >> On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote:
> > >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> > >> > > 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> > >> > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> > >> > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> > >> > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> > >> > > >> >> +#ifdef CONFIG_PM_SLEEP
> > >> > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void 
> > >> > > >> >> *context)
> > >> > > >> >> +{
> > >> > > >> >> + struct rbtn_data *rbtn_data = context;
> > >> > > >> >> +
> > >> > > >> >> + rbtn_data->suspended = false;
> > >> > > >> >> +}
> > >> > > >> >> +
> > >> > > >> >> +static int rbtn_suspend(struct device *dev)
> > >> > > >> >> +{
> > >> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
> > >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > >> > > >> >> +
> > >> > > >> >> + rbtn_data->suspended = true;
> > >> > > >> >> +
> > >> > > >> >> + return 0;
> > >> > > >> >> +}
> > >> > > >> >> +
> > >> > > >> >> +static int rbtn_resume(struct device *dev)
> > >> > > >> >> +{
> > >> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
> > >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > >> > > >> >> + acpi_status status;
> > >> > > >> >> +
> > >> > > >> >> + /*
> > >> > > >> >> +  * Clear the flag only after we received the extra
> > >> > > >> >> +  * ACPI notification.
> > >> > > >> >> +  */
> > >> > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> > >> > > >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> > >> > > >> >> + if (ACPI_FAILURE(status))
> > >> > > >> >> + rbtn_data->suspended = false;
> > >> > > >> >
> > >> > > >> > I case when acpi_os_execute success it calls 
> > >> > > >> > rbtn_acpi_clear_flag,
> > >> > > >> > right? And that will set suspended to false. When 
> > >> > > >> > acpi_os_execute fails,
> > >> > > >> > then it set suspended too to false... Then whole 
> > >> > > >> > acpi_os_execute doing
> > >> > > >> > just "barrier" after which suspended flag can be set to false. 
> > >> > > >> > So I
> > >> > > >> > think rbtn_acpi_clear_flag function is not needed here.
> > >> > > >> >
> > >> > > >> > Cannot you pass NULL or empty function pointer as callback? Or 
> > >> > > >> > what was
> > >> > > >> > reason to do that flag clearing at "two places"?
> > >> > > >>
> > >> > > >> acpi_os_execute doesn't wait for the callback to be executed, so
> > >> > > >> I can't clear the flag from rbtn_resume.
> > >> > > >
> > >> > > > acpi_os_execute calls callback asynchronously later? Or what 
> > >> > > > exactly do it?
> > >> > >
> > >> > > In this case, it adds the callback to the kacpi_notify_wq workqueue
> > >> > > for deferred execution.
> > >> >
> > >> > +Rafael for context/advice on the use of acpi_os_execute here.
> > >> >
> > >> > This is true, but a quick scan through that call path doesn't tell me 
> > >> > why we
> > >> > would need to call it here instead of just setting 
> > >> > rbtn_data->suspended = false.
> > >> > The comment suggests waiting for the event, but is that what this is 
> > >> > doing? It
> > >> > appears to me to be immediately scheduling the function to a work 
> > >> > queue, not
> > >> > waiting for the event notifier.
> > >>
> > >> I think this is supposed to work as a barrier.  That is, it will only 
> > >> run after
> > >> all events in the queue have been processed.
> > >>
> > >> I'm not sure if that's necessary, though.
> > >>
> > >> Thanks,
> > >> Rafael
> > >>
> > >
> > > Darren, Gabriele, what is state of this patch? Bug is not still fixed,
> > > right?
> > 
> > Yes, the bug is still there and this patch fixes it.
> > 
> > Just to make it clear, we need the barrier. Andrei could reproduce
> > the bug without it [1], but not with it, as he confirmed in this
> > thread [2].
> > 
> > [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001
> > [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8937
> 
> Ok, so it means that somebody (who understand ACPI) should review code
> and accept it or show what is needed to fix. Plus maybe adds more
> comments how that "barrier" works as I was first confused...
> 
> Darren, Rafael, can you do review of this patch?
> 

Yes, working toward it.

-- 
Darren Hart
Intel Open Source Technology Center

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Darren Hart]

On Thu, May 19, 2016 at 03:30:32PM +0200, Pali Rohár wrote:
> On Monday 25 April 2016 22:06:11 Gabriele Mazzotta wrote:
> > 2016-04-18 14:35 GMT+02:00 Pali Rohár :
> > > On Tuesday 29 March 2016 15:11:35 Rafael J. Wysocki wrote:
> > >> On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote:
> > >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> > >> > > 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> > >> > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> > >> > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> > >> > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> > >> > > >> >> +#ifdef CONFIG_PM_SLEEP
> > >> > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void 
> > >> > > >> >> *context)
> > >> > > >> >> +{
> > >> > > >> >> + struct rbtn_data *rbtn_data = context;
> > >> > > >> >> +
> > >> > > >> >> + rbtn_data->suspended = false;
> > >> > > >> >> +}
> > >> > > >> >> +
> > >> > > >> >> +static int rbtn_suspend(struct device *dev)
> > >> > > >> >> +{
> > >> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
> > >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > >> > > >> >> +
> > >> > > >> >> + rbtn_data->suspended = true;
> > >> > > >> >> +
> > >> > > >> >> + return 0;
> > >> > > >> >> +}
> > >> > > >> >> +
> > >> > > >> >> +static int rbtn_resume(struct device *dev)
> > >> > > >> >> +{
> > >> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
> > >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > >> > > >> >> + acpi_status status;
> > >> > > >> >> +
> > >> > > >> >> + /*
> > >> > > >> >> +  * Clear the flag only after we received the extra
> > >> > > >> >> +  * ACPI notification.
> > >> > > >> >> +  */
> > >> > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> > >> > > >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> > >> > > >> >> + if (ACPI_FAILURE(status))
> > >> > > >> >> + rbtn_data->suspended = false;
> > >> > > >> >
> > >> > > >> > I case when acpi_os_execute success it calls 
> > >> > > >> > rbtn_acpi_clear_flag,
> > >> > > >> > right? And that will set suspended to false. When 
> > >> > > >> > acpi_os_execute fails,
> > >> > > >> > then it set suspended too to false... Then whole 
> > >> > > >> > acpi_os_execute doing
> > >> > > >> > just "barrier" after which suspended flag can be set to false. 
> > >> > > >> > So I
> > >> > > >> > think rbtn_acpi_clear_flag function is not needed here.
> > >> > > >> >
> > >> > > >> > Cannot you pass NULL or empty function pointer as callback? Or 
> > >> > > >> > what was
> > >> > > >> > reason to do that flag clearing at "two places"?
> > >> > > >>
> > >> > > >> acpi_os_execute doesn't wait for the callback to be executed, so
> > >> > > >> I can't clear the flag from rbtn_resume.
> > >> > > >
> > >> > > > acpi_os_execute calls callback asynchronously later? Or what 
> > >> > > > exactly do it?
> > >> > >
> > >> > > In this case, it adds the callback to the kacpi_notify_wq workqueue
> > >> > > for deferred execution.
> > >> >
> > >> > +Rafael for context/advice on the use of acpi_os_execute here.
> > >> >
> > >> > This is true, but a quick scan through that call path doesn't tell me 
> > >> > why we
> > >> > would need to call it here instead of just setting 
> > >> > rbtn_data->suspended = false.
> > >> > The comment suggests waiting for the event, but is that what this is 
> > >> > doing? It
> > >> > appears to me to be immediately scheduling the function to a work 
> > >> > queue, not
> > >> > waiting for the event notifier.
> > >>
> > >> I think this is supposed to work as a barrier.  That is, it will only 
> > >> run after
> > >> all events in the queue have been processed.
> > >>
> > >> I'm not sure if that's necessary, though.
> > >>
> > >> Thanks,
> > >> Rafael
> > >>
> > >
> > > Darren, Gabriele, what is state of this patch? Bug is not still fixed,
> > > right?
> > 
> > Yes, the bug is still there and this patch fixes it.
> > 
> > Just to make it clear, we need the barrier. Andrei could reproduce
> > the bug without it [1], but not with it, as he confirmed in this
> > thread [2].
> > 
> > [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001
> > [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8937
> 
> Ok, so it means that somebody (who understand ACPI) should review code
> and accept it or show what is needed to fix. Plus maybe adds more
> comments how that "barrier" works as I was first confused...
> 
> Darren, Rafael, can you do review of this patch?
> 

Yes, working toward it.

-- 
Darren Hart
Intel Open Source Technology Center

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Pali Rohár]

On Monday 25 April 2016 22:06:11 Gabriele Mazzotta wrote:
> 2016-04-18 14:35 GMT+02:00 Pali Rohár :
> > On Tuesday 29 March 2016 15:11:35 Rafael J. Wysocki wrote:
> >> On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote:
> >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> >> > > 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> >> > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> >> > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> >> > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> >> > > >> >> +#ifdef CONFIG_PM_SLEEP
> >> > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void 
> >> > > >> >> *context)
> >> > > >> >> +{
> >> > > >> >> + struct rbtn_data *rbtn_data = context;
> >> > > >> >> +
> >> > > >> >> + rbtn_data->suspended = false;
> >> > > >> >> +}
> >> > > >> >> +
> >> > > >> >> +static int rbtn_suspend(struct device *dev)
> >> > > >> >> +{
> >> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
> >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> > > >> >> +
> >> > > >> >> + rbtn_data->suspended = true;
> >> > > >> >> +
> >> > > >> >> + return 0;
> >> > > >> >> +}
> >> > > >> >> +
> >> > > >> >> +static int rbtn_resume(struct device *dev)
> >> > > >> >> +{
> >> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
> >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> > > >> >> + acpi_status status;
> >> > > >> >> +
> >> > > >> >> + /*
> >> > > >> >> +  * Clear the flag only after we received the extra
> >> > > >> >> +  * ACPI notification.
> >> > > >> >> +  */
> >> > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> >> > > >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> >> > > >> >> + if (ACPI_FAILURE(status))
> >> > > >> >> + rbtn_data->suspended = false;
> >> > > >> >
> >> > > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
> >> > > >> > right? And that will set suspended to false. When acpi_os_execute 
> >> > > >> > fails,
> >> > > >> > then it set suspended too to false... Then whole acpi_os_execute 
> >> > > >> > doing
> >> > > >> > just "barrier" after which suspended flag can be set to false. So 
> >> > > >> > I
> >> > > >> > think rbtn_acpi_clear_flag function is not needed here.
> >> > > >> >
> >> > > >> > Cannot you pass NULL or empty function pointer as callback? Or 
> >> > > >> > what was
> >> > > >> > reason to do that flag clearing at "two places"?
> >> > > >>
> >> > > >> acpi_os_execute doesn't wait for the callback to be executed, so
> >> > > >> I can't clear the flag from rbtn_resume.
> >> > > >
> >> > > > acpi_os_execute calls callback asynchronously later? Or what exactly 
> >> > > > do it?
> >> > >
> >> > > In this case, it adds the callback to the kacpi_notify_wq workqueue
> >> > > for deferred execution.
> >> >
> >> > +Rafael for context/advice on the use of acpi_os_execute here.
> >> >
> >> > This is true, but a quick scan through that call path doesn't tell me 
> >> > why we
> >> > would need to call it here instead of just setting rbtn_data->suspended 
> >> > = false.
> >> > The comment suggests waiting for the event, but is that what this is 
> >> > doing? It
> >> > appears to me to be immediately scheduling the function to a work queue, 
> >> > not
> >> > waiting for the event notifier.
> >>
> >> I think this is supposed to work as a barrier.  That is, it will only run 
> >> after
> >> all events in the queue have been processed.
> >>
> >> I'm not sure if that's necessary, though.
> >>
> >> Thanks,
> >> Rafael
> >>
> >
> > Darren, Gabriele, what is state of this patch? Bug is not still fixed,
> > right?
> 
> Yes, the bug is still there and this patch fixes it.
> 
> Just to make it clear, we need the barrier. Andrei could reproduce
> the bug without it [1], but not with it, as he confirmed in this
> thread [2].
> 
> [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001
> [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8937

Ok, so it means that somebody (who understand ACPI) should review code
and accept it or show what is needed to fix. Plus maybe adds more
comments how that "barrier" works as I was first confused...

Darren, Rafael, can you do review of this patch?

-- 
Pali Rohár
pali.ro...@gmail.com

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Pali Rohár]

On Monday 25 April 2016 22:06:11 Gabriele Mazzotta wrote:
> 2016-04-18 14:35 GMT+02:00 Pali Rohár :
> > On Tuesday 29 March 2016 15:11:35 Rafael J. Wysocki wrote:
> >> On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote:
> >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> >> > > 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> >> > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> >> > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> >> > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> >> > > >> >> +#ifdef CONFIG_PM_SLEEP
> >> > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void 
> >> > > >> >> *context)
> >> > > >> >> +{
> >> > > >> >> + struct rbtn_data *rbtn_data = context;
> >> > > >> >> +
> >> > > >> >> + rbtn_data->suspended = false;
> >> > > >> >> +}
> >> > > >> >> +
> >> > > >> >> +static int rbtn_suspend(struct device *dev)
> >> > > >> >> +{
> >> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
> >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> > > >> >> +
> >> > > >> >> + rbtn_data->suspended = true;
> >> > > >> >> +
> >> > > >> >> + return 0;
> >> > > >> >> +}
> >> > > >> >> +
> >> > > >> >> +static int rbtn_resume(struct device *dev)
> >> > > >> >> +{
> >> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
> >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> > > >> >> + acpi_status status;
> >> > > >> >> +
> >> > > >> >> + /*
> >> > > >> >> +  * Clear the flag only after we received the extra
> >> > > >> >> +  * ACPI notification.
> >> > > >> >> +  */
> >> > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> >> > > >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> >> > > >> >> + if (ACPI_FAILURE(status))
> >> > > >> >> + rbtn_data->suspended = false;
> >> > > >> >
> >> > > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
> >> > > >> > right? And that will set suspended to false. When acpi_os_execute 
> >> > > >> > fails,
> >> > > >> > then it set suspended too to false... Then whole acpi_os_execute 
> >> > > >> > doing
> >> > > >> > just "barrier" after which suspended flag can be set to false. So 
> >> > > >> > I
> >> > > >> > think rbtn_acpi_clear_flag function is not needed here.
> >> > > >> >
> >> > > >> > Cannot you pass NULL or empty function pointer as callback? Or 
> >> > > >> > what was
> >> > > >> > reason to do that flag clearing at "two places"?
> >> > > >>
> >> > > >> acpi_os_execute doesn't wait for the callback to be executed, so
> >> > > >> I can't clear the flag from rbtn_resume.
> >> > > >
> >> > > > acpi_os_execute calls callback asynchronously later? Or what exactly 
> >> > > > do it?
> >> > >
> >> > > In this case, it adds the callback to the kacpi_notify_wq workqueue
> >> > > for deferred execution.
> >> >
> >> > +Rafael for context/advice on the use of acpi_os_execute here.
> >> >
> >> > This is true, but a quick scan through that call path doesn't tell me 
> >> > why we
> >> > would need to call it here instead of just setting rbtn_data->suspended 
> >> > = false.
> >> > The comment suggests waiting for the event, but is that what this is 
> >> > doing? It
> >> > appears to me to be immediately scheduling the function to a work queue, 
> >> > not
> >> > waiting for the event notifier.
> >>
> >> I think this is supposed to work as a barrier.  That is, it will only run 
> >> after
> >> all events in the queue have been processed.
> >>
> >> I'm not sure if that's necessary, though.
> >>
> >> Thanks,
> >> Rafael
> >>
> >
> > Darren, Gabriele, what is state of this patch? Bug is not still fixed,
> > right?
> 
> Yes, the bug is still there and this patch fixes it.
> 
> Just to make it clear, we need the barrier. Andrei could reproduce
> the bug without it [1], but not with it, as he confirmed in this
> thread [2].
> 
> [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001
> [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8937

Ok, so it means that somebody (who understand ACPI) should review code
and accept it or show what is needed to fix. Plus maybe adds more
comments how that "barrier" works as I was first confused...

Darren, Rafael, can you do review of this patch?

-- 
Pali Rohár
pali.ro...@gmail.com

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Gabriele Mazzotta]

2016-04-18 14:35 GMT+02:00 Pali Rohár :
> On Tuesday 29 March 2016 15:11:35 Rafael J. Wysocki wrote:
>> On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote:
>> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
>> > > 2016-03-24 10:39 GMT+01:00 Pali Rohár :
>> > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
>> > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
>> > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
>> > > >> >> +#ifdef CONFIG_PM_SLEEP
>> > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
>> > > >> >> +{
>> > > >> >> + struct rbtn_data *rbtn_data = context;
>> > > >> >> +
>> > > >> >> + rbtn_data->suspended = false;
>> > > >> >> +}
>> > > >> >> +
>> > > >> >> +static int rbtn_suspend(struct device *dev)
>> > > >> >> +{
>> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
>> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> > > >> >> +
>> > > >> >> + rbtn_data->suspended = true;
>> > > >> >> +
>> > > >> >> + return 0;
>> > > >> >> +}
>> > > >> >> +
>> > > >> >> +static int rbtn_resume(struct device *dev)
>> > > >> >> +{
>> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
>> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> > > >> >> + acpi_status status;
>> > > >> >> +
>> > > >> >> + /*
>> > > >> >> +  * Clear the flag only after we received the extra
>> > > >> >> +  * ACPI notification.
>> > > >> >> +  */
>> > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
>> > > >> >> +  rbtn_acpi_clear_flag, rbtn_data);
>> > > >> >> + if (ACPI_FAILURE(status))
>> > > >> >> + rbtn_data->suspended = false;
>> > > >> >
>> > > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
>> > > >> > right? And that will set suspended to false. When acpi_os_execute 
>> > > >> > fails,
>> > > >> > then it set suspended too to false... Then whole acpi_os_execute 
>> > > >> > doing
>> > > >> > just "barrier" after which suspended flag can be set to false. So I
>> > > >> > think rbtn_acpi_clear_flag function is not needed here.
>> > > >> >
>> > > >> > Cannot you pass NULL or empty function pointer as callback? Or what 
>> > > >> > was
>> > > >> > reason to do that flag clearing at "two places"?
>> > > >>
>> > > >> acpi_os_execute doesn't wait for the callback to be executed, so
>> > > >> I can't clear the flag from rbtn_resume.
>> > > >
>> > > > acpi_os_execute calls callback asynchronously later? Or what exactly 
>> > > > do it?
>> > >
>> > > In this case, it adds the callback to the kacpi_notify_wq workqueue
>> > > for deferred execution.
>> >
>> > +Rafael for context/advice on the use of acpi_os_execute here.
>> >
>> > This is true, but a quick scan through that call path doesn't tell me why 
>> > we
>> > would need to call it here instead of just setting rbtn_data->suspended = 
>> > false.
>> > The comment suggests waiting for the event, but is that what this is 
>> > doing? It
>> > appears to me to be immediately scheduling the function to a work queue, 
>> > not
>> > waiting for the event notifier.
>>
>> I think this is supposed to work as a barrier.  That is, it will only run 
>> after
>> all events in the queue have been processed.
>>
>> I'm not sure if that's necessary, though.
>>
>> Thanks,
>> Rafael
>>
>
> Darren, Gabriele, what is state of this patch? Bug is not still fixed,
> right?

Yes, the bug is still there and this patch fixes it.

Just to make it clear, we need the barrier. Andrei could reproduce
the bug without it [1], but not with it, as he confirmed in this
thread [2].

[1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001
[2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8937

> --
> Pali Rohár
> pali.ro...@gmail.com

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Gabriele Mazzotta]

2016-04-18 14:35 GMT+02:00 Pali Rohár :
> On Tuesday 29 March 2016 15:11:35 Rafael J. Wysocki wrote:
>> On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote:
>> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
>> > > 2016-03-24 10:39 GMT+01:00 Pali Rohár :
>> > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
>> > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
>> > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
>> > > >> >> +#ifdef CONFIG_PM_SLEEP
>> > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
>> > > >> >> +{
>> > > >> >> + struct rbtn_data *rbtn_data = context;
>> > > >> >> +
>> > > >> >> + rbtn_data->suspended = false;
>> > > >> >> +}
>> > > >> >> +
>> > > >> >> +static int rbtn_suspend(struct device *dev)
>> > > >> >> +{
>> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
>> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> > > >> >> +
>> > > >> >> + rbtn_data->suspended = true;
>> > > >> >> +
>> > > >> >> + return 0;
>> > > >> >> +}
>> > > >> >> +
>> > > >> >> +static int rbtn_resume(struct device *dev)
>> > > >> >> +{
>> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
>> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> > > >> >> + acpi_status status;
>> > > >> >> +
>> > > >> >> + /*
>> > > >> >> +  * Clear the flag only after we received the extra
>> > > >> >> +  * ACPI notification.
>> > > >> >> +  */
>> > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
>> > > >> >> +  rbtn_acpi_clear_flag, rbtn_data);
>> > > >> >> + if (ACPI_FAILURE(status))
>> > > >> >> + rbtn_data->suspended = false;
>> > > >> >
>> > > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
>> > > >> > right? And that will set suspended to false. When acpi_os_execute 
>> > > >> > fails,
>> > > >> > then it set suspended too to false... Then whole acpi_os_execute 
>> > > >> > doing
>> > > >> > just "barrier" after which suspended flag can be set to false. So I
>> > > >> > think rbtn_acpi_clear_flag function is not needed here.
>> > > >> >
>> > > >> > Cannot you pass NULL or empty function pointer as callback? Or what 
>> > > >> > was
>> > > >> > reason to do that flag clearing at "two places"?
>> > > >>
>> > > >> acpi_os_execute doesn't wait for the callback to be executed, so
>> > > >> I can't clear the flag from rbtn_resume.
>> > > >
>> > > > acpi_os_execute calls callback asynchronously later? Or what exactly 
>> > > > do it?
>> > >
>> > > In this case, it adds the callback to the kacpi_notify_wq workqueue
>> > > for deferred execution.
>> >
>> > +Rafael for context/advice on the use of acpi_os_execute here.
>> >
>> > This is true, but a quick scan through that call path doesn't tell me why 
>> > we
>> > would need to call it here instead of just setting rbtn_data->suspended = 
>> > false.
>> > The comment suggests waiting for the event, but is that what this is 
>> > doing? It
>> > appears to me to be immediately scheduling the function to a work queue, 
>> > not
>> > waiting for the event notifier.
>>
>> I think this is supposed to work as a barrier.  That is, it will only run 
>> after
>> all events in the queue have been processed.
>>
>> I'm not sure if that's necessary, though.
>>
>> Thanks,
>> Rafael
>>
>
> Darren, Gabriele, what is state of this patch? Bug is not still fixed,
> right?

Yes, the bug is still there and this patch fixes it.

Just to make it clear, we need the barrier. Andrei could reproduce
the bug without it [1], but not with it, as he confirmed in this
thread [2].

[1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001
[2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8937

> --
> Pali Rohár
> pali.ro...@gmail.com

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Pali Rohár]

On Tuesday 29 March 2016 15:11:35 Rafael J. Wysocki wrote:
> On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote:
> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> > > 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> > > >> >> +#ifdef CONFIG_PM_SLEEP
> > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> > > >> >> +{
> > > >> >> + struct rbtn_data *rbtn_data = context;
> > > >> >> +
> > > >> >> + rbtn_data->suspended = false;
> > > >> >> +}
> > > >> >> +
> > > >> >> +static int rbtn_suspend(struct device *dev)
> > > >> >> +{
> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > > >> >> +
> > > >> >> + rbtn_data->suspended = true;
> > > >> >> +
> > > >> >> + return 0;
> > > >> >> +}
> > > >> >> +
> > > >> >> +static int rbtn_resume(struct device *dev)
> > > >> >> +{
> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > > >> >> + acpi_status status;
> > > >> >> +
> > > >> >> + /*
> > > >> >> +  * Clear the flag only after we received the extra
> > > >> >> +  * ACPI notification.
> > > >> >> +  */
> > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> > > >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> > > >> >> + if (ACPI_FAILURE(status))
> > > >> >> + rbtn_data->suspended = false;
> > > >> >
> > > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
> > > >> > right? And that will set suspended to false. When acpi_os_execute 
> > > >> > fails,
> > > >> > then it set suspended too to false... Then whole acpi_os_execute 
> > > >> > doing
> > > >> > just "barrier" after which suspended flag can be set to false. So I
> > > >> > think rbtn_acpi_clear_flag function is not needed here.
> > > >> >
> > > >> > Cannot you pass NULL or empty function pointer as callback? Or what 
> > > >> > was
> > > >> > reason to do that flag clearing at "two places"?
> > > >>
> > > >> acpi_os_execute doesn't wait for the callback to be executed, so
> > > >> I can't clear the flag from rbtn_resume.
> > > >
> > > > acpi_os_execute calls callback asynchronously later? Or what exactly do 
> > > > it?
> > > 
> > > In this case, it adds the callback to the kacpi_notify_wq workqueue
> > > for deferred execution.
> > 
> > +Rafael for context/advice on the use of acpi_os_execute here.
> > 
> > This is true, but a quick scan through that call path doesn't tell me why we
> > would need to call it here instead of just setting rbtn_data->suspended = 
> > false.
> > The comment suggests waiting for the event, but is that what this is doing? 
> > It
> > appears to me to be immediately scheduling the function to a work queue, not
> > waiting for the event notifier.
> 
> I think this is supposed to work as a barrier.  That is, it will only run 
> after
> all events in the queue have been processed.
> 
> I'm not sure if that's necessary, though.
> 
> Thanks,
> Rafael
> 

Darren, Gabriele, what is state of this patch? Bug is not still fixed,
right?

-- 
Pali Rohár
pali.ro...@gmail.com

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Pali Rohár]

On Tuesday 29 March 2016 15:11:35 Rafael J. Wysocki wrote:
> On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote:
> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> > > 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> > > >> >> +#ifdef CONFIG_PM_SLEEP
> > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> > > >> >> +{
> > > >> >> + struct rbtn_data *rbtn_data = context;
> > > >> >> +
> > > >> >> + rbtn_data->suspended = false;
> > > >> >> +}
> > > >> >> +
> > > >> >> +static int rbtn_suspend(struct device *dev)
> > > >> >> +{
> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > > >> >> +
> > > >> >> + rbtn_data->suspended = true;
> > > >> >> +
> > > >> >> + return 0;
> > > >> >> +}
> > > >> >> +
> > > >> >> +static int rbtn_resume(struct device *dev)
> > > >> >> +{
> > > >> >> + struct acpi_device *device = to_acpi_device(dev);
> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > > >> >> + acpi_status status;
> > > >> >> +
> > > >> >> + /*
> > > >> >> +  * Clear the flag only after we received the extra
> > > >> >> +  * ACPI notification.
> > > >> >> +  */
> > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> > > >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> > > >> >> + if (ACPI_FAILURE(status))
> > > >> >> + rbtn_data->suspended = false;
> > > >> >
> > > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
> > > >> > right? And that will set suspended to false. When acpi_os_execute 
> > > >> > fails,
> > > >> > then it set suspended too to false... Then whole acpi_os_execute 
> > > >> > doing
> > > >> > just "barrier" after which suspended flag can be set to false. So I
> > > >> > think rbtn_acpi_clear_flag function is not needed here.
> > > >> >
> > > >> > Cannot you pass NULL or empty function pointer as callback? Or what 
> > > >> > was
> > > >> > reason to do that flag clearing at "two places"?
> > > >>
> > > >> acpi_os_execute doesn't wait for the callback to be executed, so
> > > >> I can't clear the flag from rbtn_resume.
> > > >
> > > > acpi_os_execute calls callback asynchronously later? Or what exactly do 
> > > > it?
> > > 
> > > In this case, it adds the callback to the kacpi_notify_wq workqueue
> > > for deferred execution.
> > 
> > +Rafael for context/advice on the use of acpi_os_execute here.
> > 
> > This is true, but a quick scan through that call path doesn't tell me why we
> > would need to call it here instead of just setting rbtn_data->suspended = 
> > false.
> > The comment suggests waiting for the event, but is that what this is doing? 
> > It
> > appears to me to be immediately scheduling the function to a work queue, not
> > waiting for the event notifier.
> 
> I think this is supposed to work as a barrier.  That is, it will only run 
> after
> all events in the queue have been processed.
> 
> I'm not sure if that's necessary, though.
> 
> Thanks,
> Rafael
> 

Darren, Gabriele, what is state of this patch? Bug is not still fixed,
right?

-- 
Pali Rohár
pali.ro...@gmail.com

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Rafael J. Wysocki]

On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote:
> On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> > 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> > >> >> +#ifdef CONFIG_PM_SLEEP
> > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> > >> >> +{
> > >> >> + struct rbtn_data *rbtn_data = context;
> > >> >> +
> > >> >> + rbtn_data->suspended = false;
> > >> >> +}
> > >> >> +
> > >> >> +static int rbtn_suspend(struct device *dev)
> > >> >> +{
> > >> >> + struct acpi_device *device = to_acpi_device(dev);
> > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > >> >> +
> > >> >> + rbtn_data->suspended = true;
> > >> >> +
> > >> >> + return 0;
> > >> >> +}
> > >> >> +
> > >> >> +static int rbtn_resume(struct device *dev)
> > >> >> +{
> > >> >> + struct acpi_device *device = to_acpi_device(dev);
> > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > >> >> + acpi_status status;
> > >> >> +
> > >> >> + /*
> > >> >> +  * Clear the flag only after we received the extra
> > >> >> +  * ACPI notification.
> > >> >> +  */
> > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> > >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> > >> >> + if (ACPI_FAILURE(status))
> > >> >> + rbtn_data->suspended = false;
> > >> >
> > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
> > >> > right? And that will set suspended to false. When acpi_os_execute 
> > >> > fails,
> > >> > then it set suspended too to false... Then whole acpi_os_execute doing
> > >> > just "barrier" after which suspended flag can be set to false. So I
> > >> > think rbtn_acpi_clear_flag function is not needed here.
> > >> >
> > >> > Cannot you pass NULL or empty function pointer as callback? Or what was
> > >> > reason to do that flag clearing at "two places"?
> > >>
> > >> acpi_os_execute doesn't wait for the callback to be executed, so
> > >> I can't clear the flag from rbtn_resume.
> > >
> > > acpi_os_execute calls callback asynchronously later? Or what exactly do 
> > > it?
> > 
> > In this case, it adds the callback to the kacpi_notify_wq workqueue
> > for deferred execution.
> 
> +Rafael for context/advice on the use of acpi_os_execute here.
> 
> This is true, but a quick scan through that call path doesn't tell me why we
> would need to call it here instead of just setting rbtn_data->suspended = 
> false.
> The comment suggests waiting for the event, but is that what this is doing? It
> appears to me to be immediately scheduling the function to a work queue, not
> waiting for the event notifier.

I think this is supposed to work as a barrier.  That is, it will only run after
all events in the queue have been processed.

I'm not sure if that's necessary, though.

Thanks,
Rafael

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Rafael J. Wysocki]

On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote:
> On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> > 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> > >> >> +#ifdef CONFIG_PM_SLEEP
> > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> > >> >> +{
> > >> >> + struct rbtn_data *rbtn_data = context;
> > >> >> +
> > >> >> + rbtn_data->suspended = false;
> > >> >> +}
> > >> >> +
> > >> >> +static int rbtn_suspend(struct device *dev)
> > >> >> +{
> > >> >> + struct acpi_device *device = to_acpi_device(dev);
> > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > >> >> +
> > >> >> + rbtn_data->suspended = true;
> > >> >> +
> > >> >> + return 0;
> > >> >> +}
> > >> >> +
> > >> >> +static int rbtn_resume(struct device *dev)
> > >> >> +{
> > >> >> + struct acpi_device *device = to_acpi_device(dev);
> > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > >> >> + acpi_status status;
> > >> >> +
> > >> >> + /*
> > >> >> +  * Clear the flag only after we received the extra
> > >> >> +  * ACPI notification.
> > >> >> +  */
> > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> > >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> > >> >> + if (ACPI_FAILURE(status))
> > >> >> + rbtn_data->suspended = false;
> > >> >
> > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
> > >> > right? And that will set suspended to false. When acpi_os_execute 
> > >> > fails,
> > >> > then it set suspended too to false... Then whole acpi_os_execute doing
> > >> > just "barrier" after which suspended flag can be set to false. So I
> > >> > think rbtn_acpi_clear_flag function is not needed here.
> > >> >
> > >> > Cannot you pass NULL or empty function pointer as callback? Or what was
> > >> > reason to do that flag clearing at "two places"?
> > >>
> > >> acpi_os_execute doesn't wait for the callback to be executed, so
> > >> I can't clear the flag from rbtn_resume.
> > >
> > > acpi_os_execute calls callback asynchronously later? Or what exactly do 
> > > it?
> > 
> > In this case, it adds the callback to the kacpi_notify_wq workqueue
> > for deferred execution.
> 
> +Rafael for context/advice on the use of acpi_os_execute here.
> 
> This is true, but a quick scan through that call path doesn't tell me why we
> would need to call it here instead of just setting rbtn_data->suspended = 
> false.
> The comment suggests waiting for the event, but is that what this is doing? It
> appears to me to be immediately scheduling the function to a work queue, not
> waiting for the event notifier.

I think this is supposed to work as a barrier.  That is, it will only run after
all events in the queue have been processed.

I'm not sure if that's necessary, though.

Thanks,
Rafael

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Gabriele Mazzotta]

2016-03-29 7:24 GMT+02:00 Darren Hart :
>
> On Mon, Mar 28, 2016 at 09:41:09PM +0200, Gabriele Mazzotta wrote:
> > 2016-03-28 20:56 GMT+02:00 Darren Hart :
> > > On Mon, Mar 28, 2016 at 07:58:09PM +0200, Gabriele Mazzotta wrote:
> > >> 2016-03-28 19:33 GMT+02:00 Darren Hart :
> > >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> > >> >> 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> > >> >> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> > >> >> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> > >> >> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> > >> >> >> >> +#ifdef CONFIG_PM_SLEEP
> > >> >> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void 
> > >> >> >> >> *context)
> > >> >> >> >> +{
> > >> >> >> >> + struct rbtn_data *rbtn_data = context;
> > >> >> >> >> +
> > >> >> >> >> + rbtn_data->suspended = false;
> > >> >> >> >> +}
> > >> >> >> >> +
> > >> >> >> >> +static int rbtn_suspend(struct device *dev)
> > >> >> >> >> +{
> > >> >> >> >> + struct acpi_device *device = to_acpi_device(dev);
> > >> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > >> >> >> >> +
> > >> >> >> >> + rbtn_data->suspended = true;
> > >> >> >> >> +
> > >> >> >> >> + return 0;
> > >> >> >> >> +}
> > >> >> >> >> +
> > >> >> >> >> +static int rbtn_resume(struct device *dev)
> > >> >> >> >> +{
> > >> >> >> >> + struct acpi_device *device = to_acpi_device(dev);
> > >> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > >> >> >> >> + acpi_status status;
> > >> >> >> >> +
> > >> >> >> >> + /*
> > >> >> >> >> +  * Clear the flag only after we received the extra
> > >> >> >> >> +  * ACPI notification.
> > >> >> >> >> +  */
> > >> >> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> > >> >> >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> > >> >> >> >> + if (ACPI_FAILURE(status))
> > >> >> >> >> + rbtn_data->suspended = false;
> > >> >> >> >
> > >> >> >> > I case when acpi_os_execute success it calls 
> > >> >> >> > rbtn_acpi_clear_flag,
> > >> >> >> > right? And that will set suspended to false. When 
> > >> >> >> > acpi_os_execute fails,
> > >> >> >> > then it set suspended too to false... Then whole acpi_os_execute 
> > >> >> >> > doing
> > >> >> >> > just "barrier" after which suspended flag can be set to false. 
> > >> >> >> > So I
> > >> >> >> > think rbtn_acpi_clear_flag function is not needed here.
> > >> >> >> >
> > >> >> >> > Cannot you pass NULL or empty function pointer as callback? Or 
> > >> >> >> > what was
> > >> >> >> > reason to do that flag clearing at "two places"?
> > >> >> >>
> > >> >> >> acpi_os_execute doesn't wait for the callback to be executed, so
> > >> >> >> I can't clear the flag from rbtn_resume.
> > >> >> >
> > >> >> > acpi_os_execute calls callback asynchronously later? Or what 
> > >> >> > exactly do it?
> > >> >>
> > >> >> In this case, it adds the callback to the kacpi_notify_wq workqueue
> > >> >> for deferred execution.
> > >> >
> > >> > +Rafael for context/advice on the use of acpi_os_execute here.
> > >> >
> > >> > This is true, but a quick scan through that call path doesn't tell me 
> > >> > why we
> > >> > would need to call it here instead of just setting 
> > >> > rbtn_data->suspended = false.
> > >> > The comment suggests waiting for the event, but is that what this is 
> > >> > doing? It
> > >> > appears to me to be immediately scheduling the function to a work 
> > >> > queue, not
> > >> > waiting for the event notifier.
> > >> >
> > >> > Also, since there is no indication to the user that a failure occurs, 
> > >> > this
> > >> > function is basically equivalent in the success and failure case (the 
> > >> > success
> > >> > case is just slower).
> > >> >
> > >> > Am I missing something critical here?
> > >>
> > >> Maybe saying that we are waiting for the extra event is not really
> > >> correct. Since the extra ACPI notification is processed by means
> > >> of kacpi_notify_wq, or at least that's my understanding, our callback
> > >> is likely going to be executed after we received the extra ACPI
> > >> notification. This was suggested by Rafael [2].
> > >
> > > I see, the workqueue is run after the event is issued. If that's the 
> > > case, how
> > > are we ensured that it will get cleared? Isn't it only some systems that 
> > > have
> > > this problem?
> > >
> > > What happens to the systems that do not send this event at resume? Does 
> > > the
> > > suspended flag remain set?
> >
> > The callback should be executed as long as acpi_os_execute doesn't
> > return an error. If the BIOS doesn't send the extra notification,
> > we uselessly wait for whatever was queued before our callback.
> >
> > On my laptop, the interval between the call to acpi_os_execute and
> > the callback execution is 

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Gabriele Mazzotta]

2016-03-29 7:24 GMT+02:00 Darren Hart :
>
> On Mon, Mar 28, 2016 at 09:41:09PM +0200, Gabriele Mazzotta wrote:
> > 2016-03-28 20:56 GMT+02:00 Darren Hart :
> > > On Mon, Mar 28, 2016 at 07:58:09PM +0200, Gabriele Mazzotta wrote:
> > >> 2016-03-28 19:33 GMT+02:00 Darren Hart :
> > >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> > >> >> 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> > >> >> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> > >> >> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> > >> >> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> > >> >> >> >> +#ifdef CONFIG_PM_SLEEP
> > >> >> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void 
> > >> >> >> >> *context)
> > >> >> >> >> +{
> > >> >> >> >> + struct rbtn_data *rbtn_data = context;
> > >> >> >> >> +
> > >> >> >> >> + rbtn_data->suspended = false;
> > >> >> >> >> +}
> > >> >> >> >> +
> > >> >> >> >> +static int rbtn_suspend(struct device *dev)
> > >> >> >> >> +{
> > >> >> >> >> + struct acpi_device *device = to_acpi_device(dev);
> > >> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > >> >> >> >> +
> > >> >> >> >> + rbtn_data->suspended = true;
> > >> >> >> >> +
> > >> >> >> >> + return 0;
> > >> >> >> >> +}
> > >> >> >> >> +
> > >> >> >> >> +static int rbtn_resume(struct device *dev)
> > >> >> >> >> +{
> > >> >> >> >> + struct acpi_device *device = to_acpi_device(dev);
> > >> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> > >> >> >> >> + acpi_status status;
> > >> >> >> >> +
> > >> >> >> >> + /*
> > >> >> >> >> +  * Clear the flag only after we received the extra
> > >> >> >> >> +  * ACPI notification.
> > >> >> >> >> +  */
> > >> >> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> > >> >> >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> > >> >> >> >> + if (ACPI_FAILURE(status))
> > >> >> >> >> + rbtn_data->suspended = false;
> > >> >> >> >
> > >> >> >> > I case when acpi_os_execute success it calls 
> > >> >> >> > rbtn_acpi_clear_flag,
> > >> >> >> > right? And that will set suspended to false. When 
> > >> >> >> > acpi_os_execute fails,
> > >> >> >> > then it set suspended too to false... Then whole acpi_os_execute 
> > >> >> >> > doing
> > >> >> >> > just "barrier" after which suspended flag can be set to false. 
> > >> >> >> > So I
> > >> >> >> > think rbtn_acpi_clear_flag function is not needed here.
> > >> >> >> >
> > >> >> >> > Cannot you pass NULL or empty function pointer as callback? Or 
> > >> >> >> > what was
> > >> >> >> > reason to do that flag clearing at "two places"?
> > >> >> >>
> > >> >> >> acpi_os_execute doesn't wait for the callback to be executed, so
> > >> >> >> I can't clear the flag from rbtn_resume.
> > >> >> >
> > >> >> > acpi_os_execute calls callback asynchronously later? Or what 
> > >> >> > exactly do it?
> > >> >>
> > >> >> In this case, it adds the callback to the kacpi_notify_wq workqueue
> > >> >> for deferred execution.
> > >> >
> > >> > +Rafael for context/advice on the use of acpi_os_execute here.
> > >> >
> > >> > This is true, but a quick scan through that call path doesn't tell me 
> > >> > why we
> > >> > would need to call it here instead of just setting 
> > >> > rbtn_data->suspended = false.
> > >> > The comment suggests waiting for the event, but is that what this is 
> > >> > doing? It
> > >> > appears to me to be immediately scheduling the function to a work 
> > >> > queue, not
> > >> > waiting for the event notifier.
> > >> >
> > >> > Also, since there is no indication to the user that a failure occurs, 
> > >> > this
> > >> > function is basically equivalent in the success and failure case (the 
> > >> > success
> > >> > case is just slower).
> > >> >
> > >> > Am I missing something critical here?
> > >>
> > >> Maybe saying that we are waiting for the extra event is not really
> > >> correct. Since the extra ACPI notification is processed by means
> > >> of kacpi_notify_wq, or at least that's my understanding, our callback
> > >> is likely going to be executed after we received the extra ACPI
> > >> notification. This was suggested by Rafael [2].
> > >
> > > I see, the workqueue is run after the event is issued. If that's the 
> > > case, how
> > > are we ensured that it will get cleared? Isn't it only some systems that 
> > > have
> > > this problem?
> > >
> > > What happens to the systems that do not send this event at resume? Does 
> > > the
> > > suspended flag remain set?
> >
> > The callback should be executed as long as acpi_os_execute doesn't
> > return an error. If the BIOS doesn't send the extra notification,
> > we uselessly wait for whatever was queued before our callback.
> >
> > On my laptop, the interval between the call to acpi_os_execute and
> > the callback execution is ~200ms (rough existimation using a couple
> > of printks), so not really noticeable. It might be more on some 

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Darren Hart]

On Mon, Mar 28, 2016 at 09:41:09PM +0200, Gabriele Mazzotta wrote:
> 2016-03-28 20:56 GMT+02:00 Darren Hart :
> > On Mon, Mar 28, 2016 at 07:58:09PM +0200, Gabriele Mazzotta wrote:
> >> 2016-03-28 19:33 GMT+02:00 Darren Hart :
> >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> >> >> 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> >> >> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> >> >> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> >> >> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> >> >> >> >> +#ifdef CONFIG_PM_SLEEP
> >> >> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> >> >> >> >> +{
> >> >> >> >> + struct rbtn_data *rbtn_data = context;
> >> >> >> >> +
> >> >> >> >> + rbtn_data->suspended = false;
> >> >> >> >> +}
> >> >> >> >> +
> >> >> >> >> +static int rbtn_suspend(struct device *dev)
> >> >> >> >> +{
> >> >> >> >> + struct acpi_device *device = to_acpi_device(dev);
> >> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> >> >> >> +
> >> >> >> >> + rbtn_data->suspended = true;
> >> >> >> >> +
> >> >> >> >> + return 0;
> >> >> >> >> +}
> >> >> >> >> +
> >> >> >> >> +static int rbtn_resume(struct device *dev)
> >> >> >> >> +{
> >> >> >> >> + struct acpi_device *device = to_acpi_device(dev);
> >> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> >> >> >> + acpi_status status;
> >> >> >> >> +
> >> >> >> >> + /*
> >> >> >> >> +  * Clear the flag only after we received the extra
> >> >> >> >> +  * ACPI notification.
> >> >> >> >> +  */
> >> >> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> >> >> >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> >> >> >> >> + if (ACPI_FAILURE(status))
> >> >> >> >> + rbtn_data->suspended = false;
> >> >> >> >
> >> >> >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
> >> >> >> > right? And that will set suspended to false. When acpi_os_execute 
> >> >> >> > fails,
> >> >> >> > then it set suspended too to false... Then whole acpi_os_execute 
> >> >> >> > doing
> >> >> >> > just "barrier" after which suspended flag can be set to false. So I
> >> >> >> > think rbtn_acpi_clear_flag function is not needed here.
> >> >> >> >
> >> >> >> > Cannot you pass NULL or empty function pointer as callback? Or 
> >> >> >> > what was
> >> >> >> > reason to do that flag clearing at "two places"?
> >> >> >>
> >> >> >> acpi_os_execute doesn't wait for the callback to be executed, so
> >> >> >> I can't clear the flag from rbtn_resume.
> >> >> >
> >> >> > acpi_os_execute calls callback asynchronously later? Or what exactly 
> >> >> > do it?
> >> >>
> >> >> In this case, it adds the callback to the kacpi_notify_wq workqueue
> >> >> for deferred execution.
> >> >
> >> > +Rafael for context/advice on the use of acpi_os_execute here.
> >> >
> >> > This is true, but a quick scan through that call path doesn't tell me 
> >> > why we
> >> > would need to call it here instead of just setting rbtn_data->suspended 
> >> > = false.
> >> > The comment suggests waiting for the event, but is that what this is 
> >> > doing? It
> >> > appears to me to be immediately scheduling the function to a work queue, 
> >> > not
> >> > waiting for the event notifier.
> >> >
> >> > Also, since there is no indication to the user that a failure occurs, 
> >> > this
> >> > function is basically equivalent in the success and failure case (the 
> >> > success
> >> > case is just slower).
> >> >
> >> > Am I missing something critical here?
> >>
> >> Maybe saying that we are waiting for the extra event is not really
> >> correct. Since the extra ACPI notification is processed by means
> >> of kacpi_notify_wq, or at least that's my understanding, our callback
> >> is likely going to be executed after we received the extra ACPI
> >> notification. This was suggested by Rafael [2].
> >
> > I see, the workqueue is run after the event is issued. If that's the case, 
> > how
> > are we ensured that it will get cleared? Isn't it only some systems that 
> > have
> > this problem?
> >
> > What happens to the systems that do not send this event at resume? Does the
> > suspended flag remain set?
> 
> The callback should be executed as long as acpi_os_execute doesn't
> return an error. If the BIOS doesn't send the extra notification,
> we uselessly wait for whatever was queued before our callback.
> 
> On my laptop, the interval between the call to acpi_os_execute and
> the callback execution is ~200ms (rough existimation using a couple
> of printks), so not really noticeable. It might be more on some other
> systems, but I doubt anyone would notice.

And what triggers the callback then? Some unrelated event triggering the
workqueue I presume? I don't care to tie the masking of these events to
unrelated ones. What 

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Darren Hart]

On Mon, Mar 28, 2016 at 09:41:09PM +0200, Gabriele Mazzotta wrote:
> 2016-03-28 20:56 GMT+02:00 Darren Hart :
> > On Mon, Mar 28, 2016 at 07:58:09PM +0200, Gabriele Mazzotta wrote:
> >> 2016-03-28 19:33 GMT+02:00 Darren Hart :
> >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> >> >> 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> >> >> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> >> >> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> >> >> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> >> >> >> >> +#ifdef CONFIG_PM_SLEEP
> >> >> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> >> >> >> >> +{
> >> >> >> >> + struct rbtn_data *rbtn_data = context;
> >> >> >> >> +
> >> >> >> >> + rbtn_data->suspended = false;
> >> >> >> >> +}
> >> >> >> >> +
> >> >> >> >> +static int rbtn_suspend(struct device *dev)
> >> >> >> >> +{
> >> >> >> >> + struct acpi_device *device = to_acpi_device(dev);
> >> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> >> >> >> +
> >> >> >> >> + rbtn_data->suspended = true;
> >> >> >> >> +
> >> >> >> >> + return 0;
> >> >> >> >> +}
> >> >> >> >> +
> >> >> >> >> +static int rbtn_resume(struct device *dev)
> >> >> >> >> +{
> >> >> >> >> + struct acpi_device *device = to_acpi_device(dev);
> >> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> >> >> >> + acpi_status status;
> >> >> >> >> +
> >> >> >> >> + /*
> >> >> >> >> +  * Clear the flag only after we received the extra
> >> >> >> >> +  * ACPI notification.
> >> >> >> >> +  */
> >> >> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> >> >> >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> >> >> >> >> + if (ACPI_FAILURE(status))
> >> >> >> >> + rbtn_data->suspended = false;
> >> >> >> >
> >> >> >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
> >> >> >> > right? And that will set suspended to false. When acpi_os_execute 
> >> >> >> > fails,
> >> >> >> > then it set suspended too to false... Then whole acpi_os_execute 
> >> >> >> > doing
> >> >> >> > just "barrier" after which suspended flag can be set to false. So I
> >> >> >> > think rbtn_acpi_clear_flag function is not needed here.
> >> >> >> >
> >> >> >> > Cannot you pass NULL or empty function pointer as callback? Or 
> >> >> >> > what was
> >> >> >> > reason to do that flag clearing at "two places"?
> >> >> >>
> >> >> >> acpi_os_execute doesn't wait for the callback to be executed, so
> >> >> >> I can't clear the flag from rbtn_resume.
> >> >> >
> >> >> > acpi_os_execute calls callback asynchronously later? Or what exactly 
> >> >> > do it?
> >> >>
> >> >> In this case, it adds the callback to the kacpi_notify_wq workqueue
> >> >> for deferred execution.
> >> >
> >> > +Rafael for context/advice on the use of acpi_os_execute here.
> >> >
> >> > This is true, but a quick scan through that call path doesn't tell me 
> >> > why we
> >> > would need to call it here instead of just setting rbtn_data->suspended 
> >> > = false.
> >> > The comment suggests waiting for the event, but is that what this is 
> >> > doing? It
> >> > appears to me to be immediately scheduling the function to a work queue, 
> >> > not
> >> > waiting for the event notifier.
> >> >
> >> > Also, since there is no indication to the user that a failure occurs, 
> >> > this
> >> > function is basically equivalent in the success and failure case (the 
> >> > success
> >> > case is just slower).
> >> >
> >> > Am I missing something critical here?
> >>
> >> Maybe saying that we are waiting for the extra event is not really
> >> correct. Since the extra ACPI notification is processed by means
> >> of kacpi_notify_wq, or at least that's my understanding, our callback
> >> is likely going to be executed after we received the extra ACPI
> >> notification. This was suggested by Rafael [2].
> >
> > I see, the workqueue is run after the event is issued. If that's the case, 
> > how
> > are we ensured that it will get cleared? Isn't it only some systems that 
> > have
> > this problem?
> >
> > What happens to the systems that do not send this event at resume? Does the
> > suspended flag remain set?
> 
> The callback should be executed as long as acpi_os_execute doesn't
> return an error. If the BIOS doesn't send the extra notification,
> we uselessly wait for whatever was queued before our callback.
> 
> On my laptop, the interval between the call to acpi_os_execute and
> the callback execution is ~200ms (rough existimation using a couple
> of printks), so not really noticeable. It might be more on some other
> systems, but I doubt anyone would notice.

And what triggers the callback then? Some unrelated event triggering the
workqueue I presume? I don't care to tie the masking of these events to
unrelated ones. What guarantee do we have that they will fire? Is it possible
for that workqueue to be otherwise 

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Gabriele Mazzotta]

2016-03-28 20:56 GMT+02:00 Darren Hart :
> On Mon, Mar 28, 2016 at 07:58:09PM +0200, Gabriele Mazzotta wrote:
>> 2016-03-28 19:33 GMT+02:00 Darren Hart :
>> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
>> >> 2016-03-24 10:39 GMT+01:00 Pali Rohár :
>> >> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
>> >> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
>> >> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
>> >> >> >> +#ifdef CONFIG_PM_SLEEP
>> >> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
>> >> >> >> +{
>> >> >> >> + struct rbtn_data *rbtn_data = context;
>> >> >> >> +
>> >> >> >> + rbtn_data->suspended = false;
>> >> >> >> +}
>> >> >> >> +
>> >> >> >> +static int rbtn_suspend(struct device *dev)
>> >> >> >> +{
>> >> >> >> + struct acpi_device *device = to_acpi_device(dev);
>> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> >> >> >> +
>> >> >> >> + rbtn_data->suspended = true;
>> >> >> >> +
>> >> >> >> + return 0;
>> >> >> >> +}
>> >> >> >> +
>> >> >> >> +static int rbtn_resume(struct device *dev)
>> >> >> >> +{
>> >> >> >> + struct acpi_device *device = to_acpi_device(dev);
>> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> >> >> >> + acpi_status status;
>> >> >> >> +
>> >> >> >> + /*
>> >> >> >> +  * Clear the flag only after we received the extra
>> >> >> >> +  * ACPI notification.
>> >> >> >> +  */
>> >> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
>> >> >> >> +  rbtn_acpi_clear_flag, rbtn_data);
>> >> >> >> + if (ACPI_FAILURE(status))
>> >> >> >> + rbtn_data->suspended = false;
>> >> >> >
>> >> >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
>> >> >> > right? And that will set suspended to false. When acpi_os_execute 
>> >> >> > fails,
>> >> >> > then it set suspended too to false... Then whole acpi_os_execute 
>> >> >> > doing
>> >> >> > just "barrier" after which suspended flag can be set to false. So I
>> >> >> > think rbtn_acpi_clear_flag function is not needed here.
>> >> >> >
>> >> >> > Cannot you pass NULL or empty function pointer as callback? Or what 
>> >> >> > was
>> >> >> > reason to do that flag clearing at "two places"?
>> >> >>
>> >> >> acpi_os_execute doesn't wait for the callback to be executed, so
>> >> >> I can't clear the flag from rbtn_resume.
>> >> >
>> >> > acpi_os_execute calls callback asynchronously later? Or what exactly do 
>> >> > it?
>> >>
>> >> In this case, it adds the callback to the kacpi_notify_wq workqueue
>> >> for deferred execution.
>> >
>> > +Rafael for context/advice on the use of acpi_os_execute here.
>> >
>> > This is true, but a quick scan through that call path doesn't tell me why 
>> > we
>> > would need to call it here instead of just setting rbtn_data->suspended = 
>> > false.
>> > The comment suggests waiting for the event, but is that what this is 
>> > doing? It
>> > appears to me to be immediately scheduling the function to a work queue, 
>> > not
>> > waiting for the event notifier.
>> >
>> > Also, since there is no indication to the user that a failure occurs, this
>> > function is basically equivalent in the success and failure case (the 
>> > success
>> > case is just slower).
>> >
>> > Am I missing something critical here?
>>
>> Maybe saying that we are waiting for the extra event is not really
>> correct. Since the extra ACPI notification is processed by means
>> of kacpi_notify_wq, or at least that's my understanding, our callback
>> is likely going to be executed after we received the extra ACPI
>> notification. This was suggested by Rafael [2].
>
> I see, the workqueue is run after the event is issued. If that's the case, how
> are we ensured that it will get cleared? Isn't it only some systems that have
> this problem?
>
> What happens to the systems that do not send this event at resume? Does the
> suspended flag remain set?

The callback should be executed as long as acpi_os_execute doesn't
return an error. If the BIOS doesn't send the extra notification,
we uselessly wait for whatever was queued before our callback.

On my laptop, the interval between the call to acpi_os_execute and
the callback execution is ~200ms (rough existimation using a couple
of printks), so not really noticeable. It might be more on some other
systems, but I doubt anyone would notice.

>>
>> The problem with setting the flag directly from the resume callback
>> is that the extra notification might arrive after we cleared the
>> flag, causing spurious input events [1].
>>
>> [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001
>> [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8201
>>
>> >
>> >>
>> >> > --
>> >> > Pali Rohár
>> >> > pali.ro...@gmail.com
>> >>
>> >
>> > --
>> > Darren Hart
>> > 

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Gabriele Mazzotta]

2016-03-28 20:56 GMT+02:00 Darren Hart :
> On Mon, Mar 28, 2016 at 07:58:09PM +0200, Gabriele Mazzotta wrote:
>> 2016-03-28 19:33 GMT+02:00 Darren Hart :
>> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
>> >> 2016-03-24 10:39 GMT+01:00 Pali Rohár :
>> >> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
>> >> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
>> >> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
>> >> >> >> +#ifdef CONFIG_PM_SLEEP
>> >> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
>> >> >> >> +{
>> >> >> >> + struct rbtn_data *rbtn_data = context;
>> >> >> >> +
>> >> >> >> + rbtn_data->suspended = false;
>> >> >> >> +}
>> >> >> >> +
>> >> >> >> +static int rbtn_suspend(struct device *dev)
>> >> >> >> +{
>> >> >> >> + struct acpi_device *device = to_acpi_device(dev);
>> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> >> >> >> +
>> >> >> >> + rbtn_data->suspended = true;
>> >> >> >> +
>> >> >> >> + return 0;
>> >> >> >> +}
>> >> >> >> +
>> >> >> >> +static int rbtn_resume(struct device *dev)
>> >> >> >> +{
>> >> >> >> + struct acpi_device *device = to_acpi_device(dev);
>> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> >> >> >> + acpi_status status;
>> >> >> >> +
>> >> >> >> + /*
>> >> >> >> +  * Clear the flag only after we received the extra
>> >> >> >> +  * ACPI notification.
>> >> >> >> +  */
>> >> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
>> >> >> >> +  rbtn_acpi_clear_flag, rbtn_data);
>> >> >> >> + if (ACPI_FAILURE(status))
>> >> >> >> + rbtn_data->suspended = false;
>> >> >> >
>> >> >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
>> >> >> > right? And that will set suspended to false. When acpi_os_execute 
>> >> >> > fails,
>> >> >> > then it set suspended too to false... Then whole acpi_os_execute 
>> >> >> > doing
>> >> >> > just "barrier" after which suspended flag can be set to false. So I
>> >> >> > think rbtn_acpi_clear_flag function is not needed here.
>> >> >> >
>> >> >> > Cannot you pass NULL or empty function pointer as callback? Or what 
>> >> >> > was
>> >> >> > reason to do that flag clearing at "two places"?
>> >> >>
>> >> >> acpi_os_execute doesn't wait for the callback to be executed, so
>> >> >> I can't clear the flag from rbtn_resume.
>> >> >
>> >> > acpi_os_execute calls callback asynchronously later? Or what exactly do 
>> >> > it?
>> >>
>> >> In this case, it adds the callback to the kacpi_notify_wq workqueue
>> >> for deferred execution.
>> >
>> > +Rafael for context/advice on the use of acpi_os_execute here.
>> >
>> > This is true, but a quick scan through that call path doesn't tell me why 
>> > we
>> > would need to call it here instead of just setting rbtn_data->suspended = 
>> > false.
>> > The comment suggests waiting for the event, but is that what this is 
>> > doing? It
>> > appears to me to be immediately scheduling the function to a work queue, 
>> > not
>> > waiting for the event notifier.
>> >
>> > Also, since there is no indication to the user that a failure occurs, this
>> > function is basically equivalent in the success and failure case (the 
>> > success
>> > case is just slower).
>> >
>> > Am I missing something critical here?
>>
>> Maybe saying that we are waiting for the extra event is not really
>> correct. Since the extra ACPI notification is processed by means
>> of kacpi_notify_wq, or at least that's my understanding, our callback
>> is likely going to be executed after we received the extra ACPI
>> notification. This was suggested by Rafael [2].
>
> I see, the workqueue is run after the event is issued. If that's the case, how
> are we ensured that it will get cleared? Isn't it only some systems that have
> this problem?
>
> What happens to the systems that do not send this event at resume? Does the
> suspended flag remain set?

The callback should be executed as long as acpi_os_execute doesn't
return an error. If the BIOS doesn't send the extra notification,
we uselessly wait for whatever was queued before our callback.

On my laptop, the interval between the call to acpi_os_execute and
the callback execution is ~200ms (rough existimation using a couple
of printks), so not really noticeable. It might be more on some other
systems, but I doubt anyone would notice.

>>
>> The problem with setting the flag directly from the resume callback
>> is that the extra notification might arrive after we cleared the
>> flag, causing spurious input events [1].
>>
>> [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001
>> [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8201
>>
>> >
>> >>
>> >> > --
>> >> > Pali Rohár
>> >> > pali.ro...@gmail.com
>> >>
>> >
>> > --
>> > Darren Hart
>> > Intel Open Source Technology Center
>>
>
> --
> Darren Hart
> Intel Open Source Technology 

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Darren Hart]

On Mon, Mar 28, 2016 at 07:58:09PM +0200, Gabriele Mazzotta wrote:
> 2016-03-28 19:33 GMT+02:00 Darren Hart :
> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> >> 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> >> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> >> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> >> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> >> >> >> +#ifdef CONFIG_PM_SLEEP
> >> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> >> >> >> +{
> >> >> >> + struct rbtn_data *rbtn_data = context;
> >> >> >> +
> >> >> >> + rbtn_data->suspended = false;
> >> >> >> +}
> >> >> >> +
> >> >> >> +static int rbtn_suspend(struct device *dev)
> >> >> >> +{
> >> >> >> + struct acpi_device *device = to_acpi_device(dev);
> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> >> >> +
> >> >> >> + rbtn_data->suspended = true;
> >> >> >> +
> >> >> >> + return 0;
> >> >> >> +}
> >> >> >> +
> >> >> >> +static int rbtn_resume(struct device *dev)
> >> >> >> +{
> >> >> >> + struct acpi_device *device = to_acpi_device(dev);
> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> >> >> + acpi_status status;
> >> >> >> +
> >> >> >> + /*
> >> >> >> +  * Clear the flag only after we received the extra
> >> >> >> +  * ACPI notification.
> >> >> >> +  */
> >> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> >> >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> >> >> >> + if (ACPI_FAILURE(status))
> >> >> >> + rbtn_data->suspended = false;
> >> >> >
> >> >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
> >> >> > right? And that will set suspended to false. When acpi_os_execute 
> >> >> > fails,
> >> >> > then it set suspended too to false... Then whole acpi_os_execute doing
> >> >> > just "barrier" after which suspended flag can be set to false. So I
> >> >> > think rbtn_acpi_clear_flag function is not needed here.
> >> >> >
> >> >> > Cannot you pass NULL or empty function pointer as callback? Or what 
> >> >> > was
> >> >> > reason to do that flag clearing at "two places"?
> >> >>
> >> >> acpi_os_execute doesn't wait for the callback to be executed, so
> >> >> I can't clear the flag from rbtn_resume.
> >> >
> >> > acpi_os_execute calls callback asynchronously later? Or what exactly do 
> >> > it?
> >>
> >> In this case, it adds the callback to the kacpi_notify_wq workqueue
> >> for deferred execution.
> >
> > +Rafael for context/advice on the use of acpi_os_execute here.
> >
> > This is true, but a quick scan through that call path doesn't tell me why we
> > would need to call it here instead of just setting rbtn_data->suspended = 
> > false.
> > The comment suggests waiting for the event, but is that what this is doing? 
> > It
> > appears to me to be immediately scheduling the function to a work queue, not
> > waiting for the event notifier.
> >
> > Also, since there is no indication to the user that a failure occurs, this
> > function is basically equivalent in the success and failure case (the 
> > success
> > case is just slower).
> >
> > Am I missing something critical here?
> 
> Maybe saying that we are waiting for the extra event is not really
> correct. Since the extra ACPI notification is processed by means
> of kacpi_notify_wq, or at least that's my understanding, our callback
> is likely going to be executed after we received the extra ACPI
> notification. This was suggested by Rafael [2].

I see, the workqueue is run after the event is issued. If that's the case, how
are we ensured that it will get cleared? Isn't it only some systems that have
this problem?

What happens to the systems that do not send this event at resume? Does the
suspended flag remain set?

> 
> The problem with setting the flag directly from the resume callback
> is that the extra notification might arrive after we cleared the
> flag, causing spurious input events [1].
> 
> [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001
> [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8201
> 
> >
> >>
> >> > --
> >> > Pali Rohár
> >> > pali.ro...@gmail.com
> >>
> >
> > --
> > Darren Hart
> > Intel Open Source Technology Center
> 

-- 
Darren Hart
Intel Open Source Technology Center

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Darren Hart]

On Mon, Mar 28, 2016 at 07:58:09PM +0200, Gabriele Mazzotta wrote:
> 2016-03-28 19:33 GMT+02:00 Darren Hart :
> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> >> 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> >> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> >> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> >> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> >> >> >> +#ifdef CONFIG_PM_SLEEP
> >> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> >> >> >> +{
> >> >> >> + struct rbtn_data *rbtn_data = context;
> >> >> >> +
> >> >> >> + rbtn_data->suspended = false;
> >> >> >> +}
> >> >> >> +
> >> >> >> +static int rbtn_suspend(struct device *dev)
> >> >> >> +{
> >> >> >> + struct acpi_device *device = to_acpi_device(dev);
> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> >> >> +
> >> >> >> + rbtn_data->suspended = true;
> >> >> >> +
> >> >> >> + return 0;
> >> >> >> +}
> >> >> >> +
> >> >> >> +static int rbtn_resume(struct device *dev)
> >> >> >> +{
> >> >> >> + struct acpi_device *device = to_acpi_device(dev);
> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> >> >> + acpi_status status;
> >> >> >> +
> >> >> >> + /*
> >> >> >> +  * Clear the flag only after we received the extra
> >> >> >> +  * ACPI notification.
> >> >> >> +  */
> >> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> >> >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> >> >> >> + if (ACPI_FAILURE(status))
> >> >> >> + rbtn_data->suspended = false;
> >> >> >
> >> >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
> >> >> > right? And that will set suspended to false. When acpi_os_execute 
> >> >> > fails,
> >> >> > then it set suspended too to false... Then whole acpi_os_execute doing
> >> >> > just "barrier" after which suspended flag can be set to false. So I
> >> >> > think rbtn_acpi_clear_flag function is not needed here.
> >> >> >
> >> >> > Cannot you pass NULL or empty function pointer as callback? Or what 
> >> >> > was
> >> >> > reason to do that flag clearing at "two places"?
> >> >>
> >> >> acpi_os_execute doesn't wait for the callback to be executed, so
> >> >> I can't clear the flag from rbtn_resume.
> >> >
> >> > acpi_os_execute calls callback asynchronously later? Or what exactly do 
> >> > it?
> >>
> >> In this case, it adds the callback to the kacpi_notify_wq workqueue
> >> for deferred execution.
> >
> > +Rafael for context/advice on the use of acpi_os_execute here.
> >
> > This is true, but a quick scan through that call path doesn't tell me why we
> > would need to call it here instead of just setting rbtn_data->suspended = 
> > false.
> > The comment suggests waiting for the event, but is that what this is doing? 
> > It
> > appears to me to be immediately scheduling the function to a work queue, not
> > waiting for the event notifier.
> >
> > Also, since there is no indication to the user that a failure occurs, this
> > function is basically equivalent in the success and failure case (the 
> > success
> > case is just slower).
> >
> > Am I missing something critical here?
> 
> Maybe saying that we are waiting for the extra event is not really
> correct. Since the extra ACPI notification is processed by means
> of kacpi_notify_wq, or at least that's my understanding, our callback
> is likely going to be executed after we received the extra ACPI
> notification. This was suggested by Rafael [2].

I see, the workqueue is run after the event is issued. If that's the case, how
are we ensured that it will get cleared? Isn't it only some systems that have
this problem?

What happens to the systems that do not send this event at resume? Does the
suspended flag remain set?

> 
> The problem with setting the flag directly from the resume callback
> is that the extra notification might arrive after we cleared the
> flag, causing spurious input events [1].
> 
> [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001
> [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8201
> 
> >
> >>
> >> > --
> >> > Pali Rohár
> >> > pali.ro...@gmail.com
> >>
> >
> > --
> > Darren Hart
> > Intel Open Source Technology Center
> 

-- 
Darren Hart
Intel Open Source Technology Center

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Gabriele Mazzotta]

2016-03-28 19:33 GMT+02:00 Darren Hart :
> On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
>> 2016-03-24 10:39 GMT+01:00 Pali Rohár :
>> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
>> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
>> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
>> >> >> +#ifdef CONFIG_PM_SLEEP
>> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
>> >> >> +{
>> >> >> + struct rbtn_data *rbtn_data = context;
>> >> >> +
>> >> >> + rbtn_data->suspended = false;
>> >> >> +}
>> >> >> +
>> >> >> +static int rbtn_suspend(struct device *dev)
>> >> >> +{
>> >> >> + struct acpi_device *device = to_acpi_device(dev);
>> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> >> >> +
>> >> >> + rbtn_data->suspended = true;
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >> +
>> >> >> +static int rbtn_resume(struct device *dev)
>> >> >> +{
>> >> >> + struct acpi_device *device = to_acpi_device(dev);
>> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> >> >> + acpi_status status;
>> >> >> +
>> >> >> + /*
>> >> >> +  * Clear the flag only after we received the extra
>> >> >> +  * ACPI notification.
>> >> >> +  */
>> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
>> >> >> +  rbtn_acpi_clear_flag, rbtn_data);
>> >> >> + if (ACPI_FAILURE(status))
>> >> >> + rbtn_data->suspended = false;
>> >> >
>> >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
>> >> > right? And that will set suspended to false. When acpi_os_execute fails,
>> >> > then it set suspended too to false... Then whole acpi_os_execute doing
>> >> > just "barrier" after which suspended flag can be set to false. So I
>> >> > think rbtn_acpi_clear_flag function is not needed here.
>> >> >
>> >> > Cannot you pass NULL or empty function pointer as callback? Or what was
>> >> > reason to do that flag clearing at "two places"?
>> >>
>> >> acpi_os_execute doesn't wait for the callback to be executed, so
>> >> I can't clear the flag from rbtn_resume.
>> >
>> > acpi_os_execute calls callback asynchronously later? Or what exactly do it?
>>
>> In this case, it adds the callback to the kacpi_notify_wq workqueue
>> for deferred execution.
>
> +Rafael for context/advice on the use of acpi_os_execute here.
>
> This is true, but a quick scan through that call path doesn't tell me why we
> would need to call it here instead of just setting rbtn_data->suspended = 
> false.
> The comment suggests waiting for the event, but is that what this is doing? It
> appears to me to be immediately scheduling the function to a work queue, not
> waiting for the event notifier.
>
> Also, since there is no indication to the user that a failure occurs, this
> function is basically equivalent in the success and failure case (the success
> case is just slower).
>
> Am I missing something critical here?

Maybe saying that we are waiting for the extra event is not really
correct. Since the extra ACPI notification is processed by means
of kacpi_notify_wq, or at least that's my understanding, our callback
is likely going to be executed after we received the extra ACPI
notification. This was suggested by Rafael [2].

The problem with setting the flag directly from the resume callback
is that the extra notification might arrive after we cleared the
flag, causing spurious input events [1].

[1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001
[2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8201

>
>>
>> > --
>> > Pali Rohár
>> > pali.ro...@gmail.com
>>
>
> --
> Darren Hart
> Intel Open Source Technology Center

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Gabriele Mazzotta]

2016-03-28 19:33 GMT+02:00 Darren Hart :
> On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
>> 2016-03-24 10:39 GMT+01:00 Pali Rohár :
>> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
>> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
>> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
>> >> >> +#ifdef CONFIG_PM_SLEEP
>> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
>> >> >> +{
>> >> >> + struct rbtn_data *rbtn_data = context;
>> >> >> +
>> >> >> + rbtn_data->suspended = false;
>> >> >> +}
>> >> >> +
>> >> >> +static int rbtn_suspend(struct device *dev)
>> >> >> +{
>> >> >> + struct acpi_device *device = to_acpi_device(dev);
>> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> >> >> +
>> >> >> + rbtn_data->suspended = true;
>> >> >> +
>> >> >> + return 0;
>> >> >> +}
>> >> >> +
>> >> >> +static int rbtn_resume(struct device *dev)
>> >> >> +{
>> >> >> + struct acpi_device *device = to_acpi_device(dev);
>> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> >> >> + acpi_status status;
>> >> >> +
>> >> >> + /*
>> >> >> +  * Clear the flag only after we received the extra
>> >> >> +  * ACPI notification.
>> >> >> +  */
>> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
>> >> >> +  rbtn_acpi_clear_flag, rbtn_data);
>> >> >> + if (ACPI_FAILURE(status))
>> >> >> + rbtn_data->suspended = false;
>> >> >
>> >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
>> >> > right? And that will set suspended to false. When acpi_os_execute fails,
>> >> > then it set suspended too to false... Then whole acpi_os_execute doing
>> >> > just "barrier" after which suspended flag can be set to false. So I
>> >> > think rbtn_acpi_clear_flag function is not needed here.
>> >> >
>> >> > Cannot you pass NULL or empty function pointer as callback? Or what was
>> >> > reason to do that flag clearing at "two places"?
>> >>
>> >> acpi_os_execute doesn't wait for the callback to be executed, so
>> >> I can't clear the flag from rbtn_resume.
>> >
>> > acpi_os_execute calls callback asynchronously later? Or what exactly do it?
>>
>> In this case, it adds the callback to the kacpi_notify_wq workqueue
>> for deferred execution.
>
> +Rafael for context/advice on the use of acpi_os_execute here.
>
> This is true, but a quick scan through that call path doesn't tell me why we
> would need to call it here instead of just setting rbtn_data->suspended = 
> false.
> The comment suggests waiting for the event, but is that what this is doing? It
> appears to me to be immediately scheduling the function to a work queue, not
> waiting for the event notifier.
>
> Also, since there is no indication to the user that a failure occurs, this
> function is basically equivalent in the success and failure case (the success
> case is just slower).
>
> Am I missing something critical here?

Maybe saying that we are waiting for the extra event is not really
correct. Since the extra ACPI notification is processed by means
of kacpi_notify_wq, or at least that's my understanding, our callback
is likely going to be executed after we received the extra ACPI
notification. This was suggested by Rafael [2].

The problem with setting the flag directly from the resume callback
is that the extra notification might arrive after we cleared the
flag, causing spurious input events [1].

[1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001
[2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8201

>
>>
>> > --
>> > Pali Rohár
>> > pali.ro...@gmail.com
>>
>
> --
> Darren Hart
> Intel Open Source Technology Center

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Darren Hart]

On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> >> >> +#ifdef CONFIG_PM_SLEEP
> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> >> >> +{
> >> >> + struct rbtn_data *rbtn_data = context;
> >> >> +
> >> >> + rbtn_data->suspended = false;
> >> >> +}
> >> >> +
> >> >> +static int rbtn_suspend(struct device *dev)
> >> >> +{
> >> >> + struct acpi_device *device = to_acpi_device(dev);
> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> >> +
> >> >> + rbtn_data->suspended = true;
> >> >> +
> >> >> + return 0;
> >> >> +}
> >> >> +
> >> >> +static int rbtn_resume(struct device *dev)
> >> >> +{
> >> >> + struct acpi_device *device = to_acpi_device(dev);
> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> >> + acpi_status status;
> >> >> +
> >> >> + /*
> >> >> +  * Clear the flag only after we received the extra
> >> >> +  * ACPI notification.
> >> >> +  */
> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> >> >> + if (ACPI_FAILURE(status))
> >> >> + rbtn_data->suspended = false;
> >> >
> >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
> >> > right? And that will set suspended to false. When acpi_os_execute fails,
> >> > then it set suspended too to false... Then whole acpi_os_execute doing
> >> > just "barrier" after which suspended flag can be set to false. So I
> >> > think rbtn_acpi_clear_flag function is not needed here.
> >> >
> >> > Cannot you pass NULL or empty function pointer as callback? Or what was
> >> > reason to do that flag clearing at "two places"?
> >>
> >> acpi_os_execute doesn't wait for the callback to be executed, so
> >> I can't clear the flag from rbtn_resume.
> >
> > acpi_os_execute calls callback asynchronously later? Or what exactly do it?
> 
> In this case, it adds the callback to the kacpi_notify_wq workqueue
> for deferred execution.

+Rafael for context/advice on the use of acpi_os_execute here.

This is true, but a quick scan through that call path doesn't tell me why we
would need to call it here instead of just setting rbtn_data->suspended = false.
The comment suggests waiting for the event, but is that what this is doing? It
appears to me to be immediately scheduling the function to a work queue, not
waiting for the event notifier.

Also, since there is no indication to the user that a failure occurs, this
function is basically equivalent in the success and failure case (the success
case is just slower).

Am I missing something critical here?



> 
> > --
> > Pali Rohár
> > pali.ro...@gmail.com
> 

-- 
Darren Hart
Intel Open Source Technology Center

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Darren Hart]

On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote:
> 2016-03-24 10:39 GMT+01:00 Pali Rohár :
> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> >> >> +#ifdef CONFIG_PM_SLEEP
> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> >> >> +{
> >> >> + struct rbtn_data *rbtn_data = context;
> >> >> +
> >> >> + rbtn_data->suspended = false;
> >> >> +}
> >> >> +
> >> >> +static int rbtn_suspend(struct device *dev)
> >> >> +{
> >> >> + struct acpi_device *device = to_acpi_device(dev);
> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> >> +
> >> >> + rbtn_data->suspended = true;
> >> >> +
> >> >> + return 0;
> >> >> +}
> >> >> +
> >> >> +static int rbtn_resume(struct device *dev)
> >> >> +{
> >> >> + struct acpi_device *device = to_acpi_device(dev);
> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> >> + acpi_status status;
> >> >> +
> >> >> + /*
> >> >> +  * Clear the flag only after we received the extra
> >> >> +  * ACPI notification.
> >> >> +  */
> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> >> >> +  rbtn_acpi_clear_flag, rbtn_data);
> >> >> + if (ACPI_FAILURE(status))
> >> >> + rbtn_data->suspended = false;
> >> >
> >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
> >> > right? And that will set suspended to false. When acpi_os_execute fails,
> >> > then it set suspended too to false... Then whole acpi_os_execute doing
> >> > just "barrier" after which suspended flag can be set to false. So I
> >> > think rbtn_acpi_clear_flag function is not needed here.
> >> >
> >> > Cannot you pass NULL or empty function pointer as callback? Or what was
> >> > reason to do that flag clearing at "two places"?
> >>
> >> acpi_os_execute doesn't wait for the callback to be executed, so
> >> I can't clear the flag from rbtn_resume.
> >
> > acpi_os_execute calls callback asynchronously later? Or what exactly do it?
> 
> In this case, it adds the callback to the kacpi_notify_wq workqueue
> for deferred execution.

+Rafael for context/advice on the use of acpi_os_execute here.

This is true, but a quick scan through that call path doesn't tell me why we
would need to call it here instead of just setting rbtn_data->suspended = false.
The comment suggests waiting for the event, but is that what this is doing? It
appears to me to be immediately scheduling the function to a work queue, not
waiting for the event notifier.

Also, since there is no indication to the user that a failure occurs, this
function is basically equivalent in the success and failure case (the success
case is just slower).

Am I missing something critical here?



> 
> > --
> > Pali Rohár
> > pali.ro...@gmail.com
> 

-- 
Darren Hart
Intel Open Source Technology Center

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Gabriele Mazzotta]

2016-03-24 10:39 GMT+01:00 Pali Rohár :
> On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
>> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
>> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
>> >> +#ifdef CONFIG_PM_SLEEP
>> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
>> >> +{
>> >> + struct rbtn_data *rbtn_data = context;
>> >> +
>> >> + rbtn_data->suspended = false;
>> >> +}
>> >> +
>> >> +static int rbtn_suspend(struct device *dev)
>> >> +{
>> >> + struct acpi_device *device = to_acpi_device(dev);
>> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> >> +
>> >> + rbtn_data->suspended = true;
>> >> +
>> >> + return 0;
>> >> +}
>> >> +
>> >> +static int rbtn_resume(struct device *dev)
>> >> +{
>> >> + struct acpi_device *device = to_acpi_device(dev);
>> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> >> + acpi_status status;
>> >> +
>> >> + /*
>> >> +  * Clear the flag only after we received the extra
>> >> +  * ACPI notification.
>> >> +  */
>> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
>> >> +  rbtn_acpi_clear_flag, rbtn_data);
>> >> + if (ACPI_FAILURE(status))
>> >> + rbtn_data->suspended = false;
>> >
>> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
>> > right? And that will set suspended to false. When acpi_os_execute fails,
>> > then it set suspended too to false... Then whole acpi_os_execute doing
>> > just "barrier" after which suspended flag can be set to false. So I
>> > think rbtn_acpi_clear_flag function is not needed here.
>> >
>> > Cannot you pass NULL or empty function pointer as callback? Or what was
>> > reason to do that flag clearing at "two places"?
>>
>> acpi_os_execute doesn't wait for the callback to be executed, so
>> I can't clear the flag from rbtn_resume.
>
> acpi_os_execute calls callback asynchronously later? Or what exactly do it?

In this case, it adds the callback to the kacpi_notify_wq workqueue
for deferred execution.

> --
> Pali Rohár
> pali.ro...@gmail.com

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Gabriele Mazzotta]

2016-03-24 10:39 GMT+01:00 Pali Rohár :
> On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
>> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
>> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
>> >> +#ifdef CONFIG_PM_SLEEP
>> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
>> >> +{
>> >> + struct rbtn_data *rbtn_data = context;
>> >> +
>> >> + rbtn_data->suspended = false;
>> >> +}
>> >> +
>> >> +static int rbtn_suspend(struct device *dev)
>> >> +{
>> >> + struct acpi_device *device = to_acpi_device(dev);
>> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> >> +
>> >> + rbtn_data->suspended = true;
>> >> +
>> >> + return 0;
>> >> +}
>> >> +
>> >> +static int rbtn_resume(struct device *dev)
>> >> +{
>> >> + struct acpi_device *device = to_acpi_device(dev);
>> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> >> + acpi_status status;
>> >> +
>> >> + /*
>> >> +  * Clear the flag only after we received the extra
>> >> +  * ACPI notification.
>> >> +  */
>> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
>> >> +  rbtn_acpi_clear_flag, rbtn_data);
>> >> + if (ACPI_FAILURE(status))
>> >> + rbtn_data->suspended = false;
>> >
>> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
>> > right? And that will set suspended to false. When acpi_os_execute fails,
>> > then it set suspended too to false... Then whole acpi_os_execute doing
>> > just "barrier" after which suspended flag can be set to false. So I
>> > think rbtn_acpi_clear_flag function is not needed here.
>> >
>> > Cannot you pass NULL or empty function pointer as callback? Or what was
>> > reason to do that flag clearing at "two places"?
>>
>> acpi_os_execute doesn't wait for the callback to be executed, so
>> I can't clear the flag from rbtn_resume.
>
> acpi_os_execute calls callback asynchronously later? Or what exactly do it?

In this case, it adds the callback to the kacpi_notify_wq workqueue
for deferred execution.

> --
> Pali Rohár
> pali.ro...@gmail.com

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Pali Rohár]

On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> >> +#ifdef CONFIG_PM_SLEEP
> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> >> +{
> >> + struct rbtn_data *rbtn_data = context;
> >> +
> >> + rbtn_data->suspended = false;
> >> +}
> >> +
> >> +static int rbtn_suspend(struct device *dev)
> >> +{
> >> + struct acpi_device *device = to_acpi_device(dev);
> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> +
> >> + rbtn_data->suspended = true;
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +static int rbtn_resume(struct device *dev)
> >> +{
> >> + struct acpi_device *device = to_acpi_device(dev);
> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> + acpi_status status;
> >> +
> >> + /*
> >> +  * Clear the flag only after we received the extra
> >> +  * ACPI notification.
> >> +  */
> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> >> +  rbtn_acpi_clear_flag, rbtn_data);
> >> + if (ACPI_FAILURE(status))
> >> + rbtn_data->suspended = false;
> >
> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
> > right? And that will set suspended to false. When acpi_os_execute fails,
> > then it set suspended too to false... Then whole acpi_os_execute doing
> > just "barrier" after which suspended flag can be set to false. So I
> > think rbtn_acpi_clear_flag function is not needed here.
> >
> > Cannot you pass NULL or empty function pointer as callback? Or what was
> > reason to do that flag clearing at "two places"?
> 
> acpi_os_execute doesn't wait for the callback to be executed, so
> I can't clear the flag from rbtn_resume.

acpi_os_execute calls callback asynchronously later? Or what exactly do it?

-- 
Pali Rohár
pali.ro...@gmail.com

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Pali Rohár]

On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote:
> 2016-03-21 13:17 GMT+01:00 Pali Rohár :
> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> >> +#ifdef CONFIG_PM_SLEEP
> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> >> +{
> >> + struct rbtn_data *rbtn_data = context;
> >> +
> >> + rbtn_data->suspended = false;
> >> +}
> >> +
> >> +static int rbtn_suspend(struct device *dev)
> >> +{
> >> + struct acpi_device *device = to_acpi_device(dev);
> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> +
> >> + rbtn_data->suspended = true;
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +static int rbtn_resume(struct device *dev)
> >> +{
> >> + struct acpi_device *device = to_acpi_device(dev);
> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> >> + acpi_status status;
> >> +
> >> + /*
> >> +  * Clear the flag only after we received the extra
> >> +  * ACPI notification.
> >> +  */
> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> >> +  rbtn_acpi_clear_flag, rbtn_data);
> >> + if (ACPI_FAILURE(status))
> >> + rbtn_data->suspended = false;
> >
> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
> > right? And that will set suspended to false. When acpi_os_execute fails,
> > then it set suspended too to false... Then whole acpi_os_execute doing
> > just "barrier" after which suspended flag can be set to false. So I
> > think rbtn_acpi_clear_flag function is not needed here.
> >
> > Cannot you pass NULL or empty function pointer as callback? Or what was
> > reason to do that flag clearing at "two places"?
> 
> acpi_os_execute doesn't wait for the callback to be executed, so
> I can't clear the flag from rbtn_resume.

acpi_os_execute calls callback asynchronously later? Or what exactly do it?

-- 
Pali Rohár
pali.ro...@gmail.com

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Gabriele Mazzotta]

2016-03-21 13:17 GMT+01:00 Pali Rohár :
> On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
>> +#ifdef CONFIG_PM_SLEEP
>> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
>> +{
>> + struct rbtn_data *rbtn_data = context;
>> +
>> + rbtn_data->suspended = false;
>> +}
>> +
>> +static int rbtn_suspend(struct device *dev)
>> +{
>> + struct acpi_device *device = to_acpi_device(dev);
>> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> +
>> + rbtn_data->suspended = true;
>> +
>> + return 0;
>> +}
>> +
>> +static int rbtn_resume(struct device *dev)
>> +{
>> + struct acpi_device *device = to_acpi_device(dev);
>> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> + acpi_status status;
>> +
>> + /*
>> +  * Clear the flag only after we received the extra
>> +  * ACPI notification.
>> +  */
>> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
>> +  rbtn_acpi_clear_flag, rbtn_data);
>> + if (ACPI_FAILURE(status))
>> + rbtn_data->suspended = false;
>
> I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
> right? And that will set suspended to false. When acpi_os_execute fails,
> then it set suspended too to false... Then whole acpi_os_execute doing
> just "barrier" after which suspended flag can be set to false. So I
> think rbtn_acpi_clear_flag function is not needed here.
>
> Cannot you pass NULL or empty function pointer as callback? Or what was
> reason to do that flag clearing at "two places"?

acpi_os_execute doesn't wait for the callback to be executed, so
I can't clear the flag from rbtn_resume.

>> + return 0;
>> +}
>> +#endif
>
> --
> Pali Rohár
> pali.ro...@gmail.com

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Gabriele Mazzotta]

2016-03-21 13:17 GMT+01:00 Pali Rohár :
> On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
>> +#ifdef CONFIG_PM_SLEEP
>> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
>> +{
>> + struct rbtn_data *rbtn_data = context;
>> +
>> + rbtn_data->suspended = false;
>> +}
>> +
>> +static int rbtn_suspend(struct device *dev)
>> +{
>> + struct acpi_device *device = to_acpi_device(dev);
>> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> +
>> + rbtn_data->suspended = true;
>> +
>> + return 0;
>> +}
>> +
>> +static int rbtn_resume(struct device *dev)
>> +{
>> + struct acpi_device *device = to_acpi_device(dev);
>> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
>> + acpi_status status;
>> +
>> + /*
>> +  * Clear the flag only after we received the extra
>> +  * ACPI notification.
>> +  */
>> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
>> +  rbtn_acpi_clear_flag, rbtn_data);
>> + if (ACPI_FAILURE(status))
>> + rbtn_data->suspended = false;
>
> I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
> right? And that will set suspended to false. When acpi_os_execute fails,
> then it set suspended too to false... Then whole acpi_os_execute doing
> just "barrier" after which suspended flag can be set to false. So I
> think rbtn_acpi_clear_flag function is not needed here.
>
> Cannot you pass NULL or empty function pointer as callback? Or what was
> reason to do that flag clearing at "two places"?

acpi_os_execute doesn't wait for the callback to be executed, so
I can't clear the flag from rbtn_resume.

>> + return 0;
>> +}
>> +#endif
>
> --
> Pali Rohár
> pali.ro...@gmail.com

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Pali Rohár]

On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> +#ifdef CONFIG_PM_SLEEP
> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> +{
> + struct rbtn_data *rbtn_data = context;
> +
> + rbtn_data->suspended = false;
> +}
> +
> +static int rbtn_suspend(struct device *dev)
> +{
> + struct acpi_device *device = to_acpi_device(dev);
> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> +
> + rbtn_data->suspended = true;
> +
> + return 0;
> +}
> +
> +static int rbtn_resume(struct device *dev)
> +{
> + struct acpi_device *device = to_acpi_device(dev);
> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> + acpi_status status;
> +
> + /*
> +  * Clear the flag only after we received the extra
> +  * ACPI notification.
> +  */
> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> +  rbtn_acpi_clear_flag, rbtn_data);
> + if (ACPI_FAILURE(status))
> + rbtn_data->suspended = false;

I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
right? And that will set suspended to false. When acpi_os_execute fails,
then it set suspended too to false... Then whole acpi_os_execute doing
just "barrier" after which suspended flag can be set to false. So I
think rbtn_acpi_clear_flag function is not needed here.

Cannot you pass NULL or empty function pointer as callback? Or what was
reason to do that flag clearing at "two places"?

> + return 0;
> +}
> +#endif

-- 
Pali Rohár
pali.ro...@gmail.com

Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Pali Rohár]

On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> +#ifdef CONFIG_PM_SLEEP
> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> +{
> + struct rbtn_data *rbtn_data = context;
> +
> + rbtn_data->suspended = false;
> +}
> +
> +static int rbtn_suspend(struct device *dev)
> +{
> + struct acpi_device *device = to_acpi_device(dev);
> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> +
> + rbtn_data->suspended = true;
> +
> + return 0;
> +}
> +
> +static int rbtn_resume(struct device *dev)
> +{
> + struct acpi_device *device = to_acpi_device(dev);
> + struct rbtn_data *rbtn_data = acpi_driver_data(device);
> + acpi_status status;
> +
> + /*
> +  * Clear the flag only after we received the extra
> +  * ACPI notification.
> +  */
> + status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> +  rbtn_acpi_clear_flag, rbtn_data);
> + if (ACPI_FAILURE(status))
> + rbtn_data->suspended = false;

I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
right? And that will set suspended to false. When acpi_os_execute fails,
then it set suspended too to false... Then whole acpi_os_execute doing
just "barrier" after which suspended flag can be set to false. So I
think rbtn_acpi_clear_flag function is not needed here.

Cannot you pass NULL or empty function pointer as callback? Or what was
reason to do that flag clearing at "two places"?

> + return 0;
> +}
> +#endif

-- 
Pali Rohár
pali.ro...@gmail.com

[PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Gabriele Mazzotta]

Some BIOSes unconditionally send an ACPI notification to RBTN when the
system is resuming from suspend. This makes dell-rbtn send an input
event to userspace as if a function key was pressed. Prevent this by
ignoring all the notifications received while the device is suspended.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=106031
Signed-off-by: Gabriele Mazzotta 
---
Same as v2 with some comments

 drivers/platform/x86/dell-rbtn.c | 50 
 1 file changed, 50 insertions(+)

diff --git a/drivers/platform/x86/dell-rbtn.c b/drivers/platform/x86/dell-rbtn.c
index 5155278..b144b8c 100644
--- a/drivers/platform/x86/dell-rbtn.c
+++ b/drivers/platform/x86/dell-rbtn.c
@@ -28,6 +28,7 @@ struct rbtn_data {
enum rbtn_type type;
struct rfkill *rfkill;
struct input_dev *input_dev;
+   bool suspended;
 };
 
 
@@ -220,9 +221,49 @@ static const struct acpi_device_id rbtn_ids[] = {
{ "", 0 },
 };
 
+#ifdef CONFIG_PM_SLEEP
+static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
+{
+   struct rbtn_data *rbtn_data = context;
+
+   rbtn_data->suspended = false;
+}
+
+static int rbtn_suspend(struct device *dev)
+{
+   struct acpi_device *device = to_acpi_device(dev);
+   struct rbtn_data *rbtn_data = acpi_driver_data(device);
+
+   rbtn_data->suspended = true;
+
+   return 0;
+}
+
+static int rbtn_resume(struct device *dev)
+{
+   struct acpi_device *device = to_acpi_device(dev);
+   struct rbtn_data *rbtn_data = acpi_driver_data(device);
+   acpi_status status;
+
+   /*
+* Clear the flag only after we received the extra
+* ACPI notification.
+*/
+   status = acpi_os_execute(OSL_NOTIFY_HANDLER,
+rbtn_acpi_clear_flag, rbtn_data);
+   if (ACPI_FAILURE(status))
+   rbtn_data->suspended = false;
+
+   return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(rbtn_pm_ops, rbtn_suspend, rbtn_resume);
+
 static struct acpi_driver rbtn_driver = {
.name = "dell-rbtn",
.ids = rbtn_ids,
+   .drv.pm = _pm_ops,
.ops = {
.add = rbtn_add,
.remove = rbtn_remove,
@@ -384,6 +425,15 @@ static void rbtn_notify(struct acpi_device *device, u32 
event)
 {
struct rbtn_data *rbtn_data = device->driver_data;
 
+   /*
+* Some BIOSes send autonomously a notification at resume.
+* Ignore it to prevent unwanted input events.
+*/
+   if (rbtn_data->suspended) {
+   dev_dbg(>dev, "ACPI notification ignored\n");
+   return;
+   }
+
if (event != 0x80) {
dev_info(>dev, "Received unknown event (0x%x)\n",
 event);
-- 
2.8.0.rc3

[PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

[Gabriele Mazzotta]

Some BIOSes unconditionally send an ACPI notification to RBTN when the
system is resuming from suspend. This makes dell-rbtn send an input
event to userspace as if a function key was pressed. Prevent this by
ignoring all the notifications received while the device is suspended.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=106031
Signed-off-by: Gabriele Mazzotta 
---
Same as v2 with some comments

 drivers/platform/x86/dell-rbtn.c | 50 
 1 file changed, 50 insertions(+)

diff --git a/drivers/platform/x86/dell-rbtn.c b/drivers/platform/x86/dell-rbtn.c
index 5155278..b144b8c 100644
--- a/drivers/platform/x86/dell-rbtn.c
+++ b/drivers/platform/x86/dell-rbtn.c
@@ -28,6 +28,7 @@ struct rbtn_data {
enum rbtn_type type;
struct rfkill *rfkill;
struct input_dev *input_dev;
+   bool suspended;
 };
 
 
@@ -220,9 +221,49 @@ static const struct acpi_device_id rbtn_ids[] = {
{ "", 0 },
 };
 
+#ifdef CONFIG_PM_SLEEP
+static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
+{
+   struct rbtn_data *rbtn_data = context;
+
+   rbtn_data->suspended = false;
+}
+
+static int rbtn_suspend(struct device *dev)
+{
+   struct acpi_device *device = to_acpi_device(dev);
+   struct rbtn_data *rbtn_data = acpi_driver_data(device);
+
+   rbtn_data->suspended = true;
+
+   return 0;
+}
+
+static int rbtn_resume(struct device *dev)
+{
+   struct acpi_device *device = to_acpi_device(dev);
+   struct rbtn_data *rbtn_data = acpi_driver_data(device);
+   acpi_status status;
+
+   /*
+* Clear the flag only after we received the extra
+* ACPI notification.
+*/
+   status = acpi_os_execute(OSL_NOTIFY_HANDLER,
+rbtn_acpi_clear_flag, rbtn_data);
+   if (ACPI_FAILURE(status))
+   rbtn_data->suspended = false;
+
+   return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(rbtn_pm_ops, rbtn_suspend, rbtn_resume);
+
 static struct acpi_driver rbtn_driver = {
.name = "dell-rbtn",
.ids = rbtn_ids,
+   .drv.pm = _pm_ops,
.ops = {
.add = rbtn_add,
.remove = rbtn_remove,
@@ -384,6 +425,15 @@ static void rbtn_notify(struct acpi_device *device, u32 
event)
 {
struct rbtn_data *rbtn_data = device->driver_data;
 
+   /*
+* Some BIOSes send autonomously a notification at resume.
+* Ignore it to prevent unwanted input events.
+*/
+   if (rbtn_data->suspended) {
+   dev_dbg(>dev, "ACPI notification ignored\n");
+   return;
+   }
+
if (event != 0x80) {
dev_info(>dev, "Received unknown event (0x%x)\n",
 event);
-- 
2.8.0.rc3