Re: [PATCH 2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume

[Roger Quadros]

Felipe,

On 25/01/18 18:11, Roger Quadros wrote:
> Hi,
> 
> On 24/01/18 14:19, Roger Quadros wrote:
>> On 23/01/18 14:41, Roger Quadros wrote:
>>> Hi Manu,
>>>
>>> On 23/01/18 05:45, Manu Gautam wrote:
 Hi,


 On 1/22/2018 6:31 PM, Roger Quadros wrote:
> Adding/removing host/gadget controller before .pm_complete()
> causes a lock-up. Let's prevent any dual-role state change
> between .pm_prepare() and .pm_complete() to fix this.

 What kind of lock-up are you seeing? Some hardware lockup or software 
 deadlock?
 IMO using a freezable_wq for drd_work should address that?

>>>
>>> I was seeing a software deadlock. freezable_wq is a good idea. I'll try it 
>>> out.
>>
>> using freezable_wq doesn't get rid of the deadlock.
>> If I use freezable_wq plus add some delay before I do a dwc3_host_init()
>> in the work function then it starts to work.
>>
>> As dependence on delay looks fragile so I'll stick to the current 
>> implementation
>> based on .pm_prepare/complete().
>>
> 
> So I was able to reproduce the lock up with my series as well. On further 
> investigation
> this is what I see.
> 
> There are 2 different scenarios.
> 
> 1) controller in host mode prior to system suspend and switches to device 
> mode during resume.
> 
> In this case when we call dwc3_host_exit() before tasks are thawed
> xhci_plat_remove() seems to lock up at the second usb_remove_hcd() call.
> This issue is resolved by using system_freezable_wq for the _dwc3_set_mode() 
> function.
> 
> 
> 2) controller in device mode prior to system suspend and switches to host 
> mode during resume.
> 
> In this case we sleep indefinitely in _dwc3_set_mode due to
> dwc3_set_mode()->dwc3_gadget_exit()->usb_del_gadget_udc()->udc_stop()->dwc3_gadget_stop()->wait_event_lock_irq()
> 
> This is not resolved by moving the dwc3_set_mode() call to .pm_complete() nor 
> via the system_freezable_wq.
> 
> One way I could fix this is like so.
> 
> Felipe, could you please suggest a better way?
> Maybe we need to do this in dwc3_gadget_exit() before calling 
> usb_del_gadget_udc() ?

Once you let me know your opinion I can revise this series. Thanks.

> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index b417d9a..0c903c1 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -109,6 +109,7 @@ static void __dwc3_set_mode(struct work_struct *work)
>   struct dwc3 *dwc = work_to_dwc(work);
>   unsigned long flags;
>   int ret;
> + int epnum;
>  
>   if (!dwc->desired_dr_role)
>   return;
> @@ -124,6 +125,17 @@ static void __dwc3_set_mode(struct work_struct *work)
>   dwc3_host_exit(dwc);
>   break;
>   case DWC3_GCTL_PRTCAP_DEVICE:
> + spin_lock_irqsave(>lock, flags);
> + for (epnum = 2; epnum < DWC3_ENDPOINTS_NUM; epnum++) {
> + struct dwc3_ep  *dep = dwc->eps[epnum];
> +
> + if (!dep)
> + continue;
> +
> + dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
> + }
> + spin_unlock_irqrestore(>lock, flags);
> +
>   dwc3_gadget_exit(dwc);
>   dwc3_event_buffers_cleanup(dwc);
>   break;
> 

-- 
cheers,
-roger

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. 
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume

[Roger Quadros]

Felipe,

On 12/02/18 10:54, Felipe Balbi wrote:
> 
> Hi,
> 
> Roger Quadros  writes:
>> Adding/removing host/gadget controller before .pm_complete()
>> causes a lock-up. Let's prevent any dual-role state change
>> between .pm_prepare() and .pm_complete() to fix this.
>>
>> Signed-off-by: Roger Quadros 
>> ---
>>  drivers/usb/dwc3/core.c | 31 +++
>>  drivers/usb/dwc3/core.h |  5 +
>>  drivers/usb/dwc3/drd.c  | 10 ++
>>  3 files changed, 42 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>> index 42379cc..85388dd 100644
>> --- a/drivers/usb/dwc3/core.c
>> +++ b/drivers/usb/dwc3/core.c
>> @@ -1414,6 +1414,33 @@ static int dwc3_runtime_idle(struct device *dev)
>>  #endif /* CONFIG_PM */
>>  
>>  #ifdef CONFIG_PM_SLEEP
>> +static int dwc3_prepare(struct device *dev)
>> +{
>> +struct dwc3 *dwc = dev_get_drvdata(dev);
>> +unsigned long   flags;
>> +
>> +if (dwc->dr_mode == USB_DR_MODE_OTG) {
>> +spin_lock_irqsave(>lock, flags);
>> +dwc->dr_keep_role = true;
>> +spin_unlock_irqrestore(>lock, flags);
>> +}
>> +
>> +return 0;
>> +}
>> +
>> +static void dwc3_complete(struct device *dev)
>> +{
>> +struct dwc3 *dwc = dev_get_drvdata(dev);
>> +unsigned long   flags;
>> +
>> +if (dwc->dr_mode == USB_DR_MODE_OTG) {
>> +spin_lock_irqsave(>lock, flags);
>> +dwc->dr_keep_role = false;
>> +spin_unlock_irqrestore(>lock, flags);
>> +dwc3_drd_update(dwc);
>> +}
>> +}
> 
> wouldn't it be far easier to just disable OTG IRQ in prepare? and,
> perhaps, also flush_work_sync() ?
> 

There was some more discussion on this here [1]. Apparently using 
system_freezable_wq
and a patch mentioned at end of [1] is sufficient as well

[1] https://lkml.org/lkml/2018/1/25/384

Could you please share your view there?

-- 
cheers,
-roger

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. 
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume

[Felipe Balbi]

Hi,

Roger Quadros  writes:
> Adding/removing host/gadget controller before .pm_complete()
> causes a lock-up. Let's prevent any dual-role state change
> between .pm_prepare() and .pm_complete() to fix this.
>
> Signed-off-by: Roger Quadros 
> ---
>  drivers/usb/dwc3/core.c | 31 +++
>  drivers/usb/dwc3/core.h |  5 +
>  drivers/usb/dwc3/drd.c  | 10 ++
>  3 files changed, 42 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 42379cc..85388dd 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1414,6 +1414,33 @@ static int dwc3_runtime_idle(struct device *dev)
>  #endif /* CONFIG_PM */
>  
>  #ifdef CONFIG_PM_SLEEP
> +static int dwc3_prepare(struct device *dev)
> +{
> + struct dwc3 *dwc = dev_get_drvdata(dev);
> + unsigned long   flags;
> +
> + if (dwc->dr_mode == USB_DR_MODE_OTG) {
> + spin_lock_irqsave(>lock, flags);
> + dwc->dr_keep_role = true;
> + spin_unlock_irqrestore(>lock, flags);
> + }
> +
> + return 0;
> +}
> +
> +static void dwc3_complete(struct device *dev)
> +{
> + struct dwc3 *dwc = dev_get_drvdata(dev);
> + unsigned long   flags;
> +
> + if (dwc->dr_mode == USB_DR_MODE_OTG) {
> + spin_lock_irqsave(>lock, flags);
> + dwc->dr_keep_role = false;
> + spin_unlock_irqrestore(>lock, flags);
> + dwc3_drd_update(dwc);
> + }
> +}

wouldn't it be far easier to just disable OTG IRQ in prepare? and,
perhaps, also flush_work_sync() ?

-- 
balbi


signature.asc
Description: PGP signature

Re: [PATCH 2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume

[Roger Quadros]

Hi,

On 24/01/18 14:19, Roger Quadros wrote:
> On 23/01/18 14:41, Roger Quadros wrote:
>> Hi Manu,
>>
>> On 23/01/18 05:45, Manu Gautam wrote:
>>> Hi,
>>>
>>>
>>> On 1/22/2018 6:31 PM, Roger Quadros wrote:
 Adding/removing host/gadget controller before .pm_complete()
 causes a lock-up. Let's prevent any dual-role state change
 between .pm_prepare() and .pm_complete() to fix this.
>>>
>>> What kind of lock-up are you seeing? Some hardware lockup or software 
>>> deadlock?
>>> IMO using a freezable_wq for drd_work should address that?
>>>
>>
>> I was seeing a software deadlock. freezable_wq is a good idea. I'll try it 
>> out.
> 
> using freezable_wq doesn't get rid of the deadlock.
> If I use freezable_wq plus add some delay before I do a dwc3_host_init()
> in the work function then it starts to work.
> 
> As dependence on delay looks fragile so I'll stick to the current 
> implementation
> based on .pm_prepare/complete().
> 

So I was able to reproduce the lock up with my series as well. On further 
investigation
this is what I see.

There are 2 different scenarios.

1) controller in host mode prior to system suspend and switches to device mode 
during resume.

In this case when we call dwc3_host_exit() before tasks are thawed
xhci_plat_remove() seems to lock up at the second usb_remove_hcd() call.
This issue is resolved by using system_freezable_wq for the _dwc3_set_mode() 
function.


2) controller in device mode prior to system suspend and switches to host mode 
during resume.

In this case we sleep indefinitely in _dwc3_set_mode due to
dwc3_set_mode()->dwc3_gadget_exit()->usb_del_gadget_udc()->udc_stop()->dwc3_gadget_stop()->wait_event_lock_irq()

This is not resolved by moving the dwc3_set_mode() call to .pm_complete() nor 
via the system_freezable_wq.

One way I could fix this is like so.

Felipe, could you please suggest a better way?
Maybe we need to do this in dwc3_gadget_exit() before calling 
usb_del_gadget_udc() ?

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index b417d9a..0c903c1 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -109,6 +109,7 @@ static void __dwc3_set_mode(struct work_struct *work)
struct dwc3 *dwc = work_to_dwc(work);
unsigned long flags;
int ret;
+   int epnum;
 
if (!dwc->desired_dr_role)
return;
@@ -124,6 +125,17 @@ static void __dwc3_set_mode(struct work_struct *work)
dwc3_host_exit(dwc);
break;
case DWC3_GCTL_PRTCAP_DEVICE:
+   spin_lock_irqsave(>lock, flags);
+   for (epnum = 2; epnum < DWC3_ENDPOINTS_NUM; epnum++) {
+   struct dwc3_ep  *dep = dwc->eps[epnum];
+
+   if (!dep)
+   continue;
+
+   dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
+   }
+   spin_unlock_irqrestore(>lock, flags);
+
dwc3_gadget_exit(dwc);
dwc3_event_buffers_cleanup(dwc);
break;
-- 

-- 
cheers,
-roger

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. 
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume

[Roger Quadros]

On 23/01/18 14:41, Roger Quadros wrote:
> Hi Manu,
> 
> On 23/01/18 05:45, Manu Gautam wrote:
>> Hi,
>>
>>
>> On 1/22/2018 6:31 PM, Roger Quadros wrote:
>>> Adding/removing host/gadget controller before .pm_complete()
>>> causes a lock-up. Let's prevent any dual-role state change
>>> between .pm_prepare() and .pm_complete() to fix this.
>>
>> What kind of lock-up are you seeing? Some hardware lockup or software 
>> deadlock?
>> IMO using a freezable_wq for drd_work should address that?
>>
> 
> I was seeing a software deadlock. freezable_wq is a good idea. I'll try it 
> out.

using freezable_wq doesn't get rid of the deadlock.
If I use freezable_wq plus add some delay before I do a dwc3_host_init()
in the work function then it starts to work.

As dependence on delay looks fragile so I'll stick to the current implementation
based on .pm_prepare/complete().

-- 
cheers,
-roger

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. 
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume

[Roger Quadros]

Hi Manu,

On 23/01/18 05:45, Manu Gautam wrote:
> Hi,
> 
> 
> On 1/22/2018 6:31 PM, Roger Quadros wrote:
>> Adding/removing host/gadget controller before .pm_complete()
>> causes a lock-up. Let's prevent any dual-role state change
>> between .pm_prepare() and .pm_complete() to fix this.
> 
> What kind of lock-up are you seeing? Some hardware lockup or software 
> deadlock?
> IMO using a freezable_wq for drd_work should address that?
> 

I was seeing a software deadlock. freezable_wq is a good idea. I'll try it out.

> 
>>


-- 
cheers,
-roger

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. 
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume

[Manu Gautam]

Hi,


On 1/22/2018 6:31 PM, Roger Quadros wrote:
> Adding/removing host/gadget controller before .pm_complete()
> causes a lock-up. Let's prevent any dual-role state change
> between .pm_prepare() and .pm_complete() to fix this.

What kind of lock-up are you seeing? Some hardware lockup or software deadlock?
IMO using a freezable_wq for drd_work should address that?


>
> Signed-off-by: Roger Quadros 
> ---
>  drivers/usb/dwc3/core.c | 31 +++
>  drivers/usb/dwc3/core.h |  5 +
>  drivers/usb/dwc3/drd.c  | 10 ++
>  3 files changed, 42 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 42379cc..85388dd 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1414,6 +1414,33 @@ static int dwc3_runtime_idle(struct device *dev)
>  #endif /* CONFIG_PM */
>  
>  #ifdef CONFIG_PM_SLEEP
> +static int dwc3_prepare(struct device *dev)
> +{
> + struct dwc3 *dwc = dev_get_drvdata(dev);
> + unsigned long   flags;
> +
> + if (dwc->dr_mode == USB_DR_MODE_OTG) {
> + spin_lock_irqsave(>lock, flags);
> + dwc->dr_keep_role = true;
> + spin_unlock_irqrestore(>lock, flags);
> + }
> +
> + return 0;
> +}
> +
> +static void dwc3_complete(struct device *dev)
> +{
> + struct dwc3 *dwc = dev_get_drvdata(dev);
> + unsigned long   flags;
> +
> + if (dwc->dr_mode == USB_DR_MODE_OTG) {
> + spin_lock_irqsave(>lock, flags);
> + dwc->dr_keep_role = false;
> + spin_unlock_irqrestore(>lock, flags);
> + dwc3_drd_update(dwc);
> + }
> +}
> +
>  static int dwc3_suspend(struct device *dev)
>  {
>   struct dwc3 *dwc = dev_get_drvdata(dev);
> @@ -1451,6 +1478,10 @@ static const struct dev_pm_ops dwc3_dev_pm_ops = {
>   SET_SYSTEM_SLEEP_PM_OPS(dwc3_suspend, dwc3_resume)
>   SET_RUNTIME_PM_OPS(dwc3_runtime_suspend, dwc3_runtime_resume,
>   dwc3_runtime_idle)
> +#ifdef CONFIG_PM_SLEEP
> + .prepare = dwc3_prepare,
> + .complete = dwc3_complete,
> +#endif
>  };
>  
>  #ifdef CONFIG_OF
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 4a4a4c9..f5eb474 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -786,6 +786,7 @@ struct dwc3_scratchpad_array {
>   * @dr_mode: requested mode of operation
>   * @current_dr_role: current role of operation when in dual-role mode
>   * @desired_dr_role: desired role of operation when in dual-role mode
> + * @dr_keep_role: keep the current dual-role irrespective of ID changes
>   * @edev: extcon handle
>   * @edev_nb: extcon notifier
>   * @hsphy_mode: UTMI phy mode, one of following:
> @@ -901,6 +902,7 @@ struct dwc3 {
>   enum usb_dr_modedr_mode;
>   u32 current_dr_role;
>   u32 desired_dr_role;
> + booldr_keep_role;
>   struct extcon_dev   *edev;
>   struct notifier_block   edev_nb;
>   enum usb_phy_interface  hsphy_mode;
> @@ -1227,11 +1229,14 @@ static inline int 
> dwc3_send_gadget_generic_command(struct dwc3 *dwc,
>  #if IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)
>  int dwc3_drd_init(struct dwc3 *dwc);
>  void dwc3_drd_exit(struct dwc3 *dwc);
> +void dwc3_drd_update(struct dwc3 *dwc);
>  #else
>  static inline int dwc3_drd_init(struct dwc3 *dwc)
>  { return 0; }
>  static inline void dwc3_drd_exit(struct dwc3 *dwc)
>  { }
> +static inline void dwc3_drd_update(struct dwc3 *dwc);
> +{ }
>  #endif
>  
>  /* power management interface */
> diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
> index cc8ab9a..177a8be 100644
> --- a/drivers/usb/dwc3/drd.c
> +++ b/drivers/usb/dwc3/drd.c
> @@ -13,7 +13,7 @@
>  #include "core.h"
>  #include "gadget.h"
>  
> -static void dwc3_drd_update(struct dwc3 *dwc)
> +void dwc3_drd_update(struct dwc3 *dwc)
>  {
>   int id;
>  
> @@ -31,9 +31,11 @@ static int dwc3_drd_notifier(struct notifier_block *nb,
>  {
>   struct dwc3 *dwc = container_of(nb, struct dwc3, edev_nb);
>  
> - dwc3_set_mode(dwc, event ?
> -   DWC3_GCTL_PRTCAP_HOST :
> -   DWC3_GCTL_PRTCAP_DEVICE);
> + if (!dwc->dr_keep_role) {
> + dwc3_set_mode(dwc, event ?
> +   DWC3_GCTL_PRTCAP_HOST :
> +   DWC3_GCTL_PRTCAP_DEVICE);
> + }
>  
>   return NOTIFY_DONE;
>  }

-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH 2/2] usb: dwc3: drd: Fix lock-up on ID change during system suspend/resume

[Roger Quadros]

Adding/removing host/gadget controller before .pm_complete()
causes a lock-up. Let's prevent any dual-role state change
between .pm_prepare() and .pm_complete() to fix this.

Signed-off-by: Roger Quadros 
---
 drivers/usb/dwc3/core.c | 31 +++
 drivers/usb/dwc3/core.h |  5 +
 drivers/usb/dwc3/drd.c  | 10 ++
 3 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 42379cc..85388dd 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1414,6 +1414,33 @@ static int dwc3_runtime_idle(struct device *dev)
 #endif /* CONFIG_PM */
 
 #ifdef CONFIG_PM_SLEEP
+static int dwc3_prepare(struct device *dev)
+{
+   struct dwc3 *dwc = dev_get_drvdata(dev);
+   unsigned long   flags;
+
+   if (dwc->dr_mode == USB_DR_MODE_OTG) {
+   spin_lock_irqsave(>lock, flags);
+   dwc->dr_keep_role = true;
+   spin_unlock_irqrestore(>lock, flags);
+   }
+
+   return 0;
+}
+
+static void dwc3_complete(struct device *dev)
+{
+   struct dwc3 *dwc = dev_get_drvdata(dev);
+   unsigned long   flags;
+
+   if (dwc->dr_mode == USB_DR_MODE_OTG) {
+   spin_lock_irqsave(>lock, flags);
+   dwc->dr_keep_role = false;
+   spin_unlock_irqrestore(>lock, flags);
+   dwc3_drd_update(dwc);
+   }
+}
+
 static int dwc3_suspend(struct device *dev)
 {
struct dwc3 *dwc = dev_get_drvdata(dev);
@@ -1451,6 +1478,10 @@ static const struct dev_pm_ops dwc3_dev_pm_ops = {
SET_SYSTEM_SLEEP_PM_OPS(dwc3_suspend, dwc3_resume)
SET_RUNTIME_PM_OPS(dwc3_runtime_suspend, dwc3_runtime_resume,
dwc3_runtime_idle)
+#ifdef CONFIG_PM_SLEEP
+   .prepare = dwc3_prepare,
+   .complete = dwc3_complete,
+#endif
 };
 
 #ifdef CONFIG_OF
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 4a4a4c9..f5eb474 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -786,6 +786,7 @@ struct dwc3_scratchpad_array {
  * @dr_mode: requested mode of operation
  * @current_dr_role: current role of operation when in dual-role mode
  * @desired_dr_role: desired role of operation when in dual-role mode
+ * @dr_keep_role: keep the current dual-role irrespective of ID changes
  * @edev: extcon handle
  * @edev_nb: extcon notifier
  * @hsphy_mode: UTMI phy mode, one of following:
@@ -901,6 +902,7 @@ struct dwc3 {
enum usb_dr_modedr_mode;
u32 current_dr_role;
u32 desired_dr_role;
+   booldr_keep_role;
struct extcon_dev   *edev;
struct notifier_block   edev_nb;
enum usb_phy_interface  hsphy_mode;
@@ -1227,11 +1229,14 @@ static inline int 
dwc3_send_gadget_generic_command(struct dwc3 *dwc,
 #if IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)
 int dwc3_drd_init(struct dwc3 *dwc);
 void dwc3_drd_exit(struct dwc3 *dwc);
+void dwc3_drd_update(struct dwc3 *dwc);
 #else
 static inline int dwc3_drd_init(struct dwc3 *dwc)
 { return 0; }
 static inline void dwc3_drd_exit(struct dwc3 *dwc)
 { }
+static inline void dwc3_drd_update(struct dwc3 *dwc);
+{ }
 #endif
 
 /* power management interface */
diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
index cc8ab9a..177a8be 100644
--- a/drivers/usb/dwc3/drd.c
+++ b/drivers/usb/dwc3/drd.c
@@ -13,7 +13,7 @@
 #include "core.h"
 #include "gadget.h"
 
-static void dwc3_drd_update(struct dwc3 *dwc)
+void dwc3_drd_update(struct dwc3 *dwc)
 {
int id;
 
@@ -31,9 +31,11 @@ static int dwc3_drd_notifier(struct notifier_block *nb,
 {
struct dwc3 *dwc = container_of(nb, struct dwc3, edev_nb);
 
-   dwc3_set_mode(dwc, event ?
- DWC3_GCTL_PRTCAP_HOST :
- DWC3_GCTL_PRTCAP_DEVICE);
+   if (!dwc->dr_keep_role) {
+   dwc3_set_mode(dwc, event ?
+ DWC3_GCTL_PRTCAP_HOST :
+ DWC3_GCTL_PRTCAP_DEVICE);
+   }
 
return NOTIFY_DONE;
 }
-- 
cheers,
-roger

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. 
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html