On Mon, Mar 30, 2020 at 10:18:57AM +0300, Felipe Balbi wrote: > > Hi, > > Michael Grzeschik <mgr@xxxxxxxxxxxxxx> writes: > >> > dwc3_gadget_ep_disable gets called before the last request gets > >> > dequeued. > >> > > >> > In __dwc3_gadget_ep_disable all started, pending and cancelled > >> > lists for this endpoint will call dwc3_gadget_giveback in > >> > dwc3_remove_requests. > >> > > >> > After that no list containing the afterwards dequed request, > >> > therefor it is not necessary to run the dequeue routine. > >> > > >> > Signed-off-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx> > >> > --- > >> > @Lars-Peter Clausen: > >> > > >> > This patch addresses the case that not queued requests get dequeued. > >> > The only case that this happens seems on disabling the gadget. > >> > > >> > drivers/usb/dwc3/gadget.c | 3 +++ > >> > 1 file changed, 3 insertions(+) > >> > > >> > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c > >> > index 9a6f741d1db0dc..5d4fa8d6c93e49 100644 > >> > --- a/drivers/usb/dwc3/gadget.c > >> > +++ b/drivers/usb/dwc3/gadget.c > >> > @@ -1609,6 +1609,9 @@ static int dwc3_gadget_ep_dequeue(struct usb_ep *ep, > >> > > >> > trace_dwc3_ep_dequeue(req); > >> > > >> > + if (!(dep->flags & DWC3_EP_ENABLED)) > >> > + return 0; > >> > >> which driver is trying to call dequeue after the endpoint is disabled? > >> Got some tracepoints of the problem happening? > > > > I see the case when using uvc-gadget. > > > > Look into uvc_v4l2_release in uvc_v4l2.c: > > > > uvc_function_disconnect > > composite_disconnect > > reset_config > > uvc_function_disable->usb_ep_disable > > > > uvcg_video_enable > > usb_ep_dequeue > > dwc3_gadget_ep_dequeue > > Oh, I see what you mean. We get a disconnect, which disables the > endpoints, which forces all requests to be dequeued. Now I remember why > this exists: we giveback the requests from disconnect because not all > gadget drivers will call usb_ep_dequeue() if simply told about the > disconnect. Then UDC drivers have to be a little more careful and make > sure that all requests are givenback. > > In any case, why is it a problem to call usb_ep_dequeue()? Is it only > because of that dev_err()? We could just remove that message, > really. In my case, it is not a problem removing the dev_err. The ep_dequeue will only be called once for each request at the stream end. I don't know about the case Lars has mentioned. If we have to search all lists for the request every n times while in traffic, only to find out that it was not enqueued, I think it would be worth it to keep the dev_err and let these cases trigger so we have an option to find and avoid/fix these. > Eventually, I want to move more of this logic into UDC core so > udc drivers can be simplified. For that work, though, first we would > have to add a "generic" struct usb_ep_hw implementation and manage list > of requests as part of UDC core as well. I don't know about the cases you plan to abstract but it sounds like a good idea to get some gadget logic out of the drivers. Thanks, Michael -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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