Re: [systemd-devel] [WIP PATCH 2/4] ACPI: button: remove the LID input node when the state is unknown

2017-06-07 Thread Zheng, Lv 
Hi, Benjamin

> From: linux-acpi-ow...@vger.kernel.org 
> [mailto:linux-acpi-ow...@vger.kernel.org] On Behalf Of Benjamin
> Tissoires
> Subject: Re: [WIP PATCH 2/4] ACPI: button: remove the LID input node when the 
> state is unknown
> 
> Hi Lv,
> 
> On Jun 05 2017 or thereabouts, Zheng, Lv wrote:
> > Hi, Benjamin
> >
> > > From: Benjamin Tissoires [mailto:benjamin.tissoi...@redhat.com]
> > > Subject: [WIP PATCH 2/4] ACPI: button: remove the LID input node when the 
> > > state is unknown
> 
> > My dell latitude 6430u test platform sends multiple Notify(lid) before 
> > suspend and after resume.
> 
> Does this platform requires the not lid_reliable check as per this
> series? Because if it doesn't, then we should not care.

No need to mark lid_reliable.

> > This is because the aml table puts many Notify(LID, 0x80) in various 
> > control methods.
> > And not one of them but multiple of them will be invoked by various OS 
> > drivers during suspend/resume
> period.
> > I think this is not an isolated platform that will invoke multiple 
> > redundant "Notify(lid)".
> >
> > Fortunately, the lid state for the multiple notify(lid) should be same as 
> > the first "Notify(lid)".
> > I suppose this is why SW_LID is invented, as it can really filter such 
> > redundant events.
> > And user space finally can only see 1 "close" event.
> >
> > But unconditionally prepending "open" before all "close" events surely can 
> > break the logic by
> > delivering multiple "close" events to the user space.
> 
> That doesn't matter. What matters is the state of the switch, not the
> event. So if user space receives (in case we marked the switch as not
> reliable) several close events, all user space will do is realize that
> the state is still closed and will act accordingly.

OK, I tried to address this here:
https://patchwork.kernel.org/patch/9771121/

> > Another issue is, for case 5, when we use button.lid_init_state=method.
> > Unconditionally prepending "open" before driver initiated "close" event
> > sent due to acpi_lid_initialize_state(), we will see suspend/resume cycles.
> 
> Case 5 is broken anyway and needs to be handled specially. It was not
> targeted in this WIP series.

It was addressed by button.lid_init_state=open and newer systemd.
It's not broken any more.


> > Thus if we consider both cases, we should:
> > 1. put a frequency check to filter possible redundant events.
> 
> This doesn't work and should be avoided. The state of the input switch
> is known to the input layer only, and given there are spinlocks, you can
> not know if the state is actually the one you expected beforehand.
> 
> You can however add frequency checks in the input handler, but that
> would assume the input layer is not doing its job properly and so should
> be avoided.

OK, I dropped frequency check mechanism.

> > 2. distinguish AML "Notify" call and button driver initiated lid 
> > notification.
> 
> Again, we don't care if the "event" comes from ACPI, the driver itself or
> user space (libinput). All that matters is the current state of the
> input node switch, that needs to match the physical world at any time.

That depends on the final test result.
However I managed to get systemd working with case 2,4 using this commit:
https://patchwork.kernel.org/patch/9771121/

> > This is another major differences between your proposal and mine.
> >
> > First of all, I think it should be in a separate patch.
> 
> Well, that's already a patch on its own :/
> 
> >
> > Second, I have concerns related to such a change:
> > I can see that, you are trying to address a problem that:
> > The input layer requires a determined initial SW_LID state while ACPI 
> > button driver cannot offer.
> > So by adding/removing input node, you can introduce a tristate SW_LID input 
> > node.
> 
> You can put it that way. I prefer putting it: "when we export the LID
> switch input node, you are guaranteed to have the proper state".
> 
> > However I doubt if this is necessary and can solve real issues, as:
> > systemd now works fine with button driver for all cases,
> 
> I do not care about systemd or the suspend lopps introduced by systemd.
> All I care is that the kernel provides correct behavior. If systemd can
> work around some issues we see because we are too lazy to fix them in
> the kernel (this is not a personal attack, sometimes being lazy is the
> right solution), fine. But the current state of this driver doesn't
> follow the specification of the input subsystem on some platform, and
> this is what this series fixes.

No, we just can see if case 5 is properly addressed (like current systemd 233 
does),
we don't need to do anything.
So if you still insist to fix systemd 229, I just post an RFC:
https://patchwork.kernel.org/patch/9771121/

> > only desktop managers should be changed to be compliant to case 2/4/5
> 
> As long as the kernel lies, we should not even remotely envision asking
> user space to change.

By reverting back to "method" mode

Re: [systemd-devel] [WIP PATCH 2/4] ACPI: button: remove the LID input node when the state is unknown

2017-06-06 Thread Peter Hutterer 
On Tue, Jun 06, 2017 at 12:22:09PM +0200, Benjamin Tissoires wrote:
[...]
> > This is because the aml table puts many Notify(LID, 0x80) in various 
> > control methods.
> > And not one of them but multiple of them will be invoked by various OS 
> > drivers during suspend/resume period.
> > I think this is not an isolated platform that will invoke multiple 
> > redundant "Notify(lid)".
> > 
> > Fortunately, the lid state for the multiple notify(lid) should be same as 
> > the first "Notify(lid)".
> > I suppose this is why SW_LID is invented, as it can really filter such 
> > redundant events.
> > And user space finally can only see 1 "close" event.
> > 
> > But unconditionally prepending "open" before all "close" events surely can 
> > break the logic by
> > delivering multiple "close" events to the user space.
> 
> That doesn't matter. What matters is the state of the switch, not the
> event. So if user space receives (in case we marked the switch as not
> reliable) several close events, all user space will do is realize that
> the state is still closed and will act accordingly.

[...]

> Again, we don't care if the "event" comes from ACPI, the driver itself or
> user space (libinput). All that matters is the current state of the
> input node switch, that needs to match the physical world at any time.

as extra comment on those two: you cannot guarantee when e.g. libinput
checks the state. it may start up after the kernel has updated the EV_SW
state, it may close and re-open a device without notice (disabling a
device in X has that effect for example). So the EV_SW/SW_LID events are
nice to have, but we really rely on the *state* of the switch more than the
events.

Cheers,
   Peter

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Re: [systemd-devel] [WIP PATCH 2/4] ACPI: button: remove the LID input node when the state is unknown

2017-06-06 Thread Benjamin Tissoires 
Hi Lv,

On Jun 05 2017 or thereabouts, Zheng, Lv wrote:
> Hi, Benjamin
> 
> > From: Benjamin Tissoires [mailto:benjamin.tissoi...@redhat.com]
> > Subject: [WIP PATCH 2/4] ACPI: button: remove the LID input node when the 
> > state is unknown
> > 
> > Because of the variation of firmware implementation, there is a chance
> > the LID state is unknown:
> > 1. Some platforms send "open" ACPI notification to the OS and the event
> >arrive before the button driver is resumed;
> > 2. Some platforms send "open" ACPI notification to the OS, but the event
> >arrives after the button driver is resumed, ex., Samsung N210+;
> > 3. Some platforms never send an "open" ACPI notification to the OS, but
> >update the cached _LID return value to "open", and this update arrives
> >before the button driver is resumed;
> > 4. Some platforms never send an "open" ACPI notification to the OS, but
> >update the cached _LID return value to "open", but this update arrives
> >after the button driver is resumed, ex., Surface Pro 3;
> > 5. Some platforms never send an "open" ACPI notification to the OS, and
> >_LID ACPI method returns a value which stays to "close", ex.,
> >Surface Pro 1.
> > 
> > We can mark the unreliable platform (cases 2, 4, 5 above) as such and make
> > sure we do not export an input node with an unknown state to prevent
> > suspend loops.
> > 
> > The database of unreliable devices is left to userspace to handle with
> > a hwdb file and a udev rule.
> > 
> > Note that this patch removes the filtering of duplicate events when
> > calling blocking_notifier_call_chain(), but this will be addressed in
> > a following patch.
> > 
> > Signed-off-by: Benjamin Tissoires 
> > ---
> >  drivers/acpi/button.c | 207 
> > --
> >  1 file changed, 131 insertions(+), 76 deletions(-)
> > 
> > diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
> > index 48bcdca..9ad7604 100644
> > --- a/drivers/acpi/button.c
> > +++ b/drivers/acpi/button.c
> > @@ -25,6 +25,7 @@
> >  #include 
> >  #include 
> >  #include 
> > +#include 
> >  #include 
> >  #include 
> >  #include 
> > @@ -79,6 +80,8 @@ MODULE_DEVICE_TABLE(acpi, button_device_ids);
> >  static int acpi_button_add(struct acpi_device *device);
> >  static int acpi_button_remove(struct acpi_device *device);
> >  static void acpi_button_notify(struct acpi_device *device, u32 event);
> > +static int acpi_button_add_input(struct acpi_device *device);
> > +static int acpi_lid_update_reliable(struct acpi_device *device);
> > 
> >  #ifdef CONFIG_PM_SLEEP
> >  static int acpi_button_suspend(struct device *dev);
> > @@ -111,6 +114,8 @@ struct acpi_button {
> > bool suspended;
> >  };
> > 
> > +static DEFINE_MUTEX(button_input_lock);
> > +
> >  static BLOCKING_NOTIFIER_HEAD(acpi_lid_notifier);
> >  static struct acpi_device *lid_device;
> >  static u8 lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
> > @@ -119,6 +124,44 @@ static unsigned long lid_report_interval __read_mostly 
> > = 500;
> >  module_param(lid_report_interval, ulong, 0644);
> >  MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key 
> > events");
> > 
> > +static bool lid_reliable = true;
> > +
> > +static int param_set_lid_reliable(const char *val,
> > + const struct kernel_param *kp)
> > +{
> > +   bool prev_lid_reliable = lid_reliable;
> > +   int ret;
> > +
> > +   mutex_lock(_input_lock);
> > +
> > +   ret = param_set_bool(val, kp);
> > +   if (ret) {
> > +   mutex_unlock(_input_lock);
> > +   return ret;
> > +   }
> > +
> > +   /*
> > +* prevent a loop when we show up the device to userspace because
> > +* of an acpi notification, and userspace immediately removes it
> > +* by marking it as unreliable when this was already known.
> > +*/
> > +   if (lid_device && prev_lid_reliable != lid_reliable) {
> > +   ret = acpi_lid_update_reliable(lid_device);
> > +   if (ret)
> > +   lid_reliable = prev_lid_reliable;
> > +   }
> > +
> > +   mutex_unlock(_input_lock);
> > +   return ret;
> > +}
> > +
> > +static const struct kernel_param_ops lid_reliable_ops = {
> > +   .get = param_get_bool,
> > +   .set = param_set_lid_reliable,
> > +};
> > +module_param_cb(lid_reliable, _reliable_ops, _reliable, 0644);
> > +MODULE_PARM_DESC(lid_reliable, "Is the LID switch reliable (true|false)?");
> > +
> >  /* 
> > --
> >FS Interface (/proc)
> > 
> > -- 
> > */
> > @@ -142,79 +185,22 @@ static int acpi_lid_notify_state(struct acpi_device 
> > *device, int state)
> >  {
> > struct acpi_button *button = acpi_driver_data(device);
> > int ret;
> > -   ktime_t next_report;
> > -   bool do_update;
> > +
> > +   /* button_input_lock must be

Re: [systemd-devel] [WIP PATCH 2/4] ACPI: button: remove the LID input node when the state is unknown

2017-06-04 Thread Zheng, Lv 
Hi, Benjamin

> From: Benjamin Tissoires [mailto:benjamin.tissoi...@redhat.com]
> Subject: [WIP PATCH 2/4] ACPI: button: remove the LID input node when the 
> state is unknown
> 
> Because of the variation of firmware implementation, there is a chance
> the LID state is unknown:
> 1. Some platforms send "open" ACPI notification to the OS and the event
>arrive before the button driver is resumed;
> 2. Some platforms send "open" ACPI notification to the OS, but the event
>arrives after the button driver is resumed, ex., Samsung N210+;
> 3. Some platforms never send an "open" ACPI notification to the OS, but
>update the cached _LID return value to "open", and this update arrives
>before the button driver is resumed;
> 4. Some platforms never send an "open" ACPI notification to the OS, but
>update the cached _LID return value to "open", but this update arrives
>after the button driver is resumed, ex., Surface Pro 3;
> 5. Some platforms never send an "open" ACPI notification to the OS, and
>_LID ACPI method returns a value which stays to "close", ex.,
>Surface Pro 1.
> 
> We can mark the unreliable platform (cases 2, 4, 5 above) as such and make
> sure we do not export an input node with an unknown state to prevent
> suspend loops.
> 
> The database of unreliable devices is left to userspace to handle with
> a hwdb file and a udev rule.
> 
> Note that this patch removes the filtering of duplicate events when
> calling blocking_notifier_call_chain(), but this will be addressed in
> a following patch.
> 
> Signed-off-by: Benjamin Tissoires 
> ---
>  drivers/acpi/button.c | 207 
> --
>  1 file changed, 131 insertions(+), 76 deletions(-)
> 
> diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
> index 48bcdca..9ad7604 100644
> --- a/drivers/acpi/button.c
> +++ b/drivers/acpi/button.c
> @@ -25,6 +25,7 @@
>  #include 
>  #include 
>  #include 
> +#include 
>  #include 
>  #include 
>  #include 
> @@ -79,6 +80,8 @@ MODULE_DEVICE_TABLE(acpi, button_device_ids);
>  static int acpi_button_add(struct acpi_device *device);
>  static int acpi_button_remove(struct acpi_device *device);
>  static void acpi_button_notify(struct acpi_device *device, u32 event);
> +static int acpi_button_add_input(struct acpi_device *device);
> +static int acpi_lid_update_reliable(struct acpi_device *device);
> 
>  #ifdef CONFIG_PM_SLEEP
>  static int acpi_button_suspend(struct device *dev);
> @@ -111,6 +114,8 @@ struct acpi_button {
>   bool suspended;
>  };
> 
> +static DEFINE_MUTEX(button_input_lock);
> +
>  static BLOCKING_NOTIFIER_HEAD(acpi_lid_notifier);
>  static struct acpi_device *lid_device;
>  static u8 lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
> @@ -119,6 +124,44 @@ static unsigned long lid_report_interval __read_mostly = 
> 500;
>  module_param(lid_report_interval, ulong, 0644);
>  MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key 
> events");
> 
> +static bool lid_reliable = true;
> +
> +static int param_set_lid_reliable(const char *val,
> +   const struct kernel_param *kp)
> +{
> + bool prev_lid_reliable = lid_reliable;
> + int ret;
> +
> + mutex_lock(_input_lock);
> +
> + ret = param_set_bool(val, kp);
> + if (ret) {
> + mutex_unlock(_input_lock);
> + return ret;
> + }
> +
> + /*
> +  * prevent a loop when we show up the device to userspace because
> +  * of an acpi notification, and userspace immediately removes it
> +  * by marking it as unreliable when this was already known.
> +  */
> + if (lid_device && prev_lid_reliable != lid_reliable) {
> + ret = acpi_lid_update_reliable(lid_device);
> + if (ret)
> + lid_reliable = prev_lid_reliable;
> + }
> +
> + mutex_unlock(_input_lock);
> + return ret;
> +}
> +
> +static const struct kernel_param_ops lid_reliable_ops = {
> + .get = param_get_bool,
> + .set = param_set_lid_reliable,
> +};
> +module_param_cb(lid_reliable, _reliable_ops, _reliable, 0644);
> +MODULE_PARM_DESC(lid_reliable, "Is the LID switch reliable (true|false)?");
> +
>  /* --
>FS Interface (/proc)
> 
> -- */
> @@ -142,79 +185,22 @@ static int acpi_lid_notify_state(struct acpi_device 
> *device, int state)
>  {
>   struct acpi_button *button = acpi_driver_data(device);
>   int ret;
> - ktime_t next_report;
> - bool do_update;
> +
> + /* button_input_lock must be held */
> +
> + if (!button->input)
> + return 0;
> 
>   /*
> -  * In lid_init_state=ignore mode, if user opens/closes lid
> -  * frequently with "open" missing, and "last_time" is also updated
> -  * frequently, "close" cannot

[systemd-devel] [WIP PATCH 2/4] ACPI: button: remove the LID input node when the state is unknown

2017-06-01 Thread Benjamin Tissoires 
Because of the variation of firmware implementation, there is a chance
the LID state is unknown:
1. Some platforms send "open" ACPI notification to the OS and the event
   arrive before the button driver is resumed;
2. Some platforms send "open" ACPI notification to the OS, but the event
   arrives after the button driver is resumed, ex., Samsung N210+;
3. Some platforms never send an "open" ACPI notification to the OS, but
   update the cached _LID return value to "open", and this update arrives
   before the button driver is resumed;
4. Some platforms never send an "open" ACPI notification to the OS, but
   update the cached _LID return value to "open", but this update arrives
   after the button driver is resumed, ex., Surface Pro 3;
5. Some platforms never send an "open" ACPI notification to the OS, and
   _LID ACPI method returns a value which stays to "close", ex.,
   Surface Pro 1.

We can mark the unreliable platform (cases 2, 4, 5 above) as such and make
sure we do not export an input node with an unknown state to prevent
suspend loops.

The database of unreliable devices is left to userspace to handle with
a hwdb file and a udev rule.

Note that this patch removes the filtering of duplicate events when
calling blocking_notifier_call_chain(), but this will be addressed in
a following patch.

Signed-off-by: Benjamin Tissoires 
---
 drivers/acpi/button.c | 207 --
 1 file changed, 131 insertions(+), 76 deletions(-)

diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
index 48bcdca..9ad7604 100644
--- a/drivers/acpi/button.c
+++ b/drivers/acpi/button.c
@@ -25,6 +25,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -79,6 +80,8 @@ MODULE_DEVICE_TABLE(acpi, button_device_ids);
 static int acpi_button_add(struct acpi_device *device);
 static int acpi_button_remove(struct acpi_device *device);
 static void acpi_button_notify(struct acpi_device *device, u32 event);
+static int acpi_button_add_input(struct acpi_device *device);
+static int acpi_lid_update_reliable(struct acpi_device *device);
 
 #ifdef CONFIG_PM_SLEEP
 static int acpi_button_suspend(struct device *dev);
@@ -111,6 +114,8 @@ struct acpi_button {
bool suspended;
 };
 
+static DEFINE_MUTEX(button_input_lock);
+
 static BLOCKING_NOTIFIER_HEAD(acpi_lid_notifier);
 static struct acpi_device *lid_device;
 static u8 lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
@@ -119,6 +124,44 @@ static unsigned long lid_report_interval __read_mostly = 
500;
 module_param(lid_report_interval, ulong, 0644);
 MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key events");
 
+static bool lid_reliable = true;
+
+static int param_set_lid_reliable(const char *val,
+ const struct kernel_param *kp)
+{
+   bool prev_lid_reliable = lid_reliable;
+   int ret;
+
+   mutex_lock(_input_lock);
+
+   ret = param_set_bool(val, kp);
+   if (ret) {
+   mutex_unlock(_input_lock);
+   return ret;
+   }
+
+   /*
+* prevent a loop when we show up the device to userspace because
+* of an acpi notification, and userspace immediately removes it
+* by marking it as unreliable when this was already known.
+*/
+   if (lid_device && prev_lid_reliable != lid_reliable) {
+   ret = acpi_lid_update_reliable(lid_device);
+   if (ret)
+   lid_reliable = prev_lid_reliable;
+   }
+
+   mutex_unlock(_input_lock);
+   return ret;
+}
+
+static const struct kernel_param_ops lid_reliable_ops = {
+   .get = param_get_bool,
+   .set = param_set_lid_reliable,
+};
+module_param_cb(lid_reliable, _reliable_ops, _reliable, 0644);
+MODULE_PARM_DESC(lid_reliable, "Is the LID switch reliable (true|false)?");
+
 /* --
   FS Interface (/proc)
-- 
*/
@@ -142,79 +185,22 @@ static int acpi_lid_notify_state(struct acpi_device 
*device, int state)
 {
struct acpi_button *button = acpi_driver_data(device);
int ret;
-   ktime_t next_report;
-   bool do_update;
+
+   /* button_input_lock must be held */
+
+   if (!button->input)
+   return 0;
 
/*
-* In lid_init_state=ignore mode, if user opens/closes lid
-* frequently with "open" missing, and "last_time" is also updated
-* frequently, "close" cannot be delivered to the userspace.
-* So "last_time" is only updated after a timeout or an actual
-* switch.
+* If the lid is unreliable, always send an "open" event before any
+* other. The input layer will filter out the extra open if required,
+* and it will force the close event to be sent.
 */
-   if