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