On 8/3/2021 12:58 AM, Felipe Balbi wrote:
>
> Jack Pham <jackp@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxx>
>>> ---
>>> 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
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