On Tue, Jan 28, 2020 at 11:23 PM Felipe Balbi <balbi@xxxxxxxxxx> wrote: > John Stultz <john.stultz@xxxxxxxxxx> writes: > > From: Anurag Kumar Vulisha <anurag.kumar.vulisha@xxxxxxxxxx> > > > > The current code in dwc3_gadget_ep_reclaim_completed_trb() will > > check for IOC/LST bit in the event->status and returns if > > IOC/LST bit is set. This logic doesn't work if multiple TRBs > > are queued per request and the IOC/LST bit is set on the last > > TRB of that request. > > > > Consider an example where a queued request has multiple queued > > TRBs and IOC/LST bit is set only for the last TRB. In this case, > > the core generates XferComplete/XferInProgress events only for > > the last TRB (since IOC/LST are set only for the last TRB). As > > per the logic in dwc3_gadget_ep_reclaim_completed_trb() > > event->status is checked for IOC/LST bit and returns on the > > first TRB. This leaves the remaining TRBs left unhandled. > > > > Similarly, if the gadget function enqueues an unaligned request > > with sglist already in it, it should fail the same way, since we > > will append another TRB to something that already uses more than > > one TRB. > > > > To aviod this, this patch changes the code to check for IOC/LST > > bits in TRB->ctrl instead. > > > > At a practical level, this patch resolves USB transfer stalls seen > > with adb on dwc3 based HiKey960 after functionfs gadget added > > scatter-gather support around v4.20. > > > > Cc: Felipe Balbi <balbi@xxxxxxxxxx> > > Cc: Yang Fei <fei.yang@xxxxxxxxx> > > Cc: Thinh Nguyen <thinhn@xxxxxxxxxxxx> > > Cc: Tejas Joglekar <tejas.joglekar@xxxxxxxxxxxx> > > Cc: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxxxx> > > Cc: Jack Pham <jackp@xxxxxxxxxxxxxx> > > Cc: Todd Kjos <tkjos@xxxxxxxxxx> > > Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> > > Cc: Linux USB List <linux-usb@xxxxxxxxxxxxxxx> > > Cc: stable <stable@xxxxxxxxxxxxxxx> > > Tested-by: Tejas Joglekar <tejas.joglekar@xxxxxxxxxxxx> > > Reviewed-by: Thinh Nguyen <thinhn@xxxxxxxxxxxx> > > Signed-off-by: Anurag Kumar Vulisha <anurag.kumar.vulisha@xxxxxxxxxx> > > [jstultz: forward ported to mainline, reworded commit log, reworked > > to only check trb->ctrl as suggested by Felipe] > > Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx> > > since v5.5 is already merged, I'll send this to Greg once -rc1 is > tagged. It's already in my testing/fixes branch waiting for a pull > request. Great, thanks so much for queueing this! I'll be digging on the db845c side wrt the dma-api issue to hopefully get that one sorted as well. Thanks again for the help and analysis! -john
