Hi, John Stultz <john.stultz@xxxxxxxxxx> writes: > 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 no worries, it was way past the time :-) > side wrt the dma-api issue to hopefully get that one sorted as well. Thanks, that would, indeed, be great :-) > Thanks again for the help and analysis! no worries. If you find anything odd, just collect traces and I can help have a look. -- balbi
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