[PATCH] usb: dwc3: gadget: Avoid runtime resume if disabling pullup

[PATCH] usb: dwc3: gadget: Avoid runtime resume if disabling pullup

[Wesley Cheng]

If the device is already in the runtime suspended state, any call to
the pullup routine will issue a runtime resume on the DWC3 core
device.  If the USB gadget is disabling the pullup, then avoid having
to issue a runtime resume, as DWC3 gadget has already been
halted/stopped.

This fixes an issue where the following condition occurs:

usb_gadget_remove_driver()
-->usb_gadget_disconnect()
 -->dwc3_gadget_pullup(0)
  -->pm_runtime_get_sync() -> ret = 0
  -->pm_runtime_put() [async]
-->usb_gadget_udc_stop()
 -->dwc3_gadget_stop()
  -->dwc->gadget_driver = NULL
...

dwc3_suspend_common()
-->dwc3_gadget_suspend()
 -->DWC3 halt/stop routine skipped, driver_data == NULL

This leads to a situation where the DWC3 gadget is not properly
stopped, as the runtime resume would have re-enabled EP0 and event
interrupts, and since we avoided the DWC3 gadget suspend, these
resources were never disabled.

Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
---
 drivers/usb/dwc3/gadget.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index a29a4ca..5d08454 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2435,6 +2435,17 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 	}
 
 	/*
+	 * Avoid issuing a runtime resume if the device is already in the
+	 * suspended state during gadget disconnect.  DWC3 gadget was already
+	 * halted/stopped during runtime suspend.
+	 */
+	if (!is_on) {
+		pm_runtime_barrier(dwc->dev);
+		if (pm_runtime_suspended(dwc->dev))
+			return 0;
+	}
+
+	/*
 	 * Check the return value for successful resume, or error.  For a
 	 * successful resume, the DWC3 runtime PM resume routine will handle
 	 * the run stop sequence, so avoid duplicate operations here.
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH] usb: dwc3: gadget: Avoid runtime resume if disabling pullup

[Jack Pham]

Hi Wesley,

On Fri, Jul 30, 2021 at 05:29:34PM -0700, Wesley Cheng wrote:
> If the device is already in the runtime suspended state, any call to
> the pullup routine will issue a runtime resume on the DWC3 core
> device.  If the USB gadget is disabling the pullup, then avoid having
> to issue a runtime resume, as DWC3 gadget has already been
> halted/stopped.
> 
> This fixes an issue where the following condition occurs:
> 
> usb_gadget_remove_driver()
> -->usb_gadget_disconnect()
>  -->dwc3_gadget_pullup(0)
>   -->pm_runtime_get_sync() -> ret = 0
>   -->pm_runtime_put() [async]
> -->usb_gadget_udc_stop()
>  -->dwc3_gadget_stop()
>   -->dwc->gadget_driver = NULL
> ...
> 
> dwc3_suspend_common()
> -->dwc3_gadget_suspend()
>  -->DWC3 halt/stop routine skipped, driver_data == NULL
> 
> This leads to a situation where the DWC3 gadget is not properly
> stopped, as the runtime resume would have re-enabled EP0 and event
> interrupts, and since we avoided the DWC3 gadget suspend, these
> resources were never disabled.
> 
> Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
> ---
>  drivers/usb/dwc3/gadget.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index a29a4ca..5d08454 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -2435,6 +2435,17 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
>  	}
>  
>  	/*
> +	 * Avoid issuing a runtime resume if the device is already in the
> +	 * suspended state during gadget disconnect.  DWC3 gadget was already
> +	 * halted/stopped during runtime suspend.
> +	 */
> +	if (!is_on) {
> +		pm_runtime_barrier(dwc->dev);
> +		if (pm_runtime_suspended(dwc->dev))
> +			return 0;
> +	}
> +
> +	/*
>  	 * Check the return value for successful resume, or error.  For a
>  	 * successful resume, the DWC3 runtime PM resume routine will handle
>  	 * the run stop sequence, so avoid duplicate operations here.

Should this also go to stable with Fixes: 77adb8bdf422 ("usb: dwc3:
gadget: Allow runtime suspend if UDC unbinded") ?

Jack

Re: [PATCH] usb: dwc3: gadget: Avoid runtime resume if disabling pullup

[Felipe Balbi]

Jack Pham <jackp@codeaurora.org> writes:

> Hi Wesley,
>
> On Fri, Jul 30, 2021 at 05:29:34PM -0700, Wesley Cheng wrote:
>> If the device is already in the runtime suspended state, any call to
>> the pullup routine will issue a runtime resume on the DWC3 core
>> device.  If the USB gadget is disabling the pullup, then avoid having
>> to issue a runtime resume, as DWC3 gadget has already been
>> halted/stopped.
>> 
>> This fixes an issue where the following condition occurs:
>> 
>> usb_gadget_remove_driver()
>> -->usb_gadget_disconnect()
>>  -->dwc3_gadget_pullup(0)
>>   -->pm_runtime_get_sync() -> ret = 0
>>   -->pm_runtime_put() [async]
>> -->usb_gadget_udc_stop()
>>  -->dwc3_gadget_stop()
>>   -->dwc->gadget_driver = NULL
>> ...
>> 
>> dwc3_suspend_common()
>> -->dwc3_gadget_suspend()
>>  -->DWC3 halt/stop routine skipped, driver_data == NULL
>> 
>> This leads to a situation where the DWC3 gadget is not properly
>> stopped, as the runtime resume would have re-enabled EP0 and event
>> interrupts, and since we avoided the DWC3 gadget suspend, these
>> resources were never disabled.
>> 
>> Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
>> ---
>>  drivers/usb/dwc3/gadget.c | 11 +++++++++++
>>  1 file changed, 11 insertions(+)
>> 
>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>> index a29a4ca..5d08454 100644
>> --- a/drivers/usb/dwc3/gadget.c
>> +++ b/drivers/usb/dwc3/gadget.c
>> @@ -2435,6 +2435,17 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
>>  	}
>>  
>>  	/*
>> +	 * Avoid issuing a runtime resume if the device is already in the
>> +	 * suspended state during gadget disconnect.  DWC3 gadget was already
>> +	 * halted/stopped during runtime suspend.
>> +	 */
>> +	if (!is_on) {
>> +		pm_runtime_barrier(dwc->dev);
>> +		if (pm_runtime_suspended(dwc->dev))
>> +			return 0;
>> +	}
>> +
>> +	/*
>>  	 * Check the return value for successful resume, or error.  For a
>>  	 * successful resume, the DWC3 runtime PM resume routine will handle
>>  	 * the run stop sequence, so avoid duplicate operations here.
>
> Should this also go to stable with Fixes: 77adb8bdf422 ("usb: dwc3:
> gadget: Allow runtime suspend if UDC unbinded") ?

sounds like a good idea.

-- 
balbi

Re: [PATCH] usb: dwc3: gadget: Avoid runtime resume if disabling pullup

[Wesley Cheng]

On 8/3/2021 12:58 AM, Felipe Balbi wrote:
> 
> Jack Pham <jackp@codeaurora.org> writes:
> 
>> Hi Wesley,
>>
>> On Fri, Jul 30, 2021 at 05:29:34PM -0700, Wesley Cheng wrote:
>>> If the device is already in the runtime suspended state, any call to
>>> the pullup routine will issue a runtime resume on the DWC3 core
>>> device.  If the USB gadget is disabling the pullup, then avoid having
>>> to issue a runtime resume, as DWC3 gadget has already been
>>> halted/stopped.
>>>
>>> This fixes an issue where the following condition occurs:
>>>
>>> usb_gadget_remove_driver()
>>> -->usb_gadget_disconnect()
>>>  -->dwc3_gadget_pullup(0)
>>>   -->pm_runtime_get_sync() -> ret = 0
>>>   -->pm_runtime_put() [async]
>>> -->usb_gadget_udc_stop()
>>>  -->dwc3_gadget_stop()
>>>   -->dwc->gadget_driver = NULL
>>> ...
>>>
>>> dwc3_suspend_common()
>>> -->dwc3_gadget_suspend()
>>>  -->DWC3 halt/stop routine skipped, driver_data == NULL
>>>
>>> This leads to a situation where the DWC3 gadget is not properly
>>> stopped, as the runtime resume would have re-enabled EP0 and event
>>> interrupts, and since we avoided the DWC3 gadget suspend, these
>>> resources were never disabled.
>>>
>>> Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
>>> ---
>>>  drivers/usb/dwc3/gadget.c | 11 +++++++++++
>>>  1 file changed, 11 insertions(+)
>>>
>>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>>> index a29a4ca..5d08454 100644
>>> --- a/drivers/usb/dwc3/gadget.c
>>> +++ b/drivers/usb/dwc3/gadget.c
>>> @@ -2435,6 +2435,17 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
>>>  	}
>>>  
>>>  	/*
>>> +	 * Avoid issuing a runtime resume if the device is already in the
>>> +	 * suspended state during gadget disconnect.  DWC3 gadget was already
>>> +	 * halted/stopped during runtime suspend.
>>> +	 */
>>> +	if (!is_on) {
>>> +		pm_runtime_barrier(dwc->dev);
>>> +		if (pm_runtime_suspended(dwc->dev))
>>> +			return 0;
>>> +	}
>>> +
>>> +	/*
>>>  	 * Check the return value for successful resume, or error.  For a
>>>  	 * successful resume, the DWC3 runtime PM resume routine will handle
>>>  	 * the run stop sequence, so avoid duplicate operations here.

Hi Jack/Felipe,

>>
>> Should this also go to stable with Fixes: 77adb8bdf422 ("usb: dwc3:
>> gadget: Allow runtime suspend if UDC unbinded") ?
> 
> sounds like a good idea.
> 

Sure, will update the commit text with the fixes tag.  Thanks!

Regards,
Wesley Cheng

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