Hi Felipe,
Felipe Balbi wrote:
> Hi,
>
> Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> writes:
>> If an active transfer is dequeued, then the endpoint is freed to start a
>> new transfer. Make sure to clear the endpoint's transfer wait flag for
>> this case.
>>
>> Cc: stable@xxxxxxxxxxxxxxx
>> Fixes: e0d19563eb6c ("usb: dwc3: gadget: Wait for transfer completion")
>> Signed-off-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>
>> ---
>> Changes in v2:
>> - Only clear the wait flag if the selected request is of an active transfer.
>> Otherwise, any dequeue will change the endpoint's state even if it's for
>> some random request.
>>
>> drivers/usb/dwc3/gadget.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>> index 78cb4db8a6e4..9a00dcaca010 100644
>> --- a/drivers/usb/dwc3/gadget.c
>> +++ b/drivers/usb/dwc3/gadget.c
>> @@ -1763,6 +1763,8 @@ static int dwc3_gadget_ep_dequeue(struct usb_ep *ep,
>> list_for_each_entry_safe(r, t, &dep->started_list, list)
>> dwc3_gadget_move_cancelled_request(r);
>>
>> + dep->flags &= ~DWC3_EP_WAIT_TRANSFER_COMPLETE;
> I'm not sure this is correct. This could create a race condition between
> clearing this bit and getting the transfer complete interrupt. It also
> seems to break the assumptions made by
> dwc3_gadget_endpoint_trbs_complete() (actually its users), specially
> regarding ISOC endpoints.
>
> Have you verified all transfer types with this commit?
>
It shouldn't race. It's protected by the spinlock irq and it doesn't
matter whether dwc3_gadget_endpoint_trbs_complete() or this dequeue
function clears it first. The flag DWC3_EP_WAIT_TRANSFER_COMPLETE is
only applicable to stream transfer as the driver needs to wait for 1
stream to finish before starting another.
This is verified with our test environment (which includes UASP CV and
others).
BR,
Thinh
