Hi, 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> > --- > v2: > * Rework to only check trb->ctrl as suggested by Felipe > * Reword the commit message to include more of Felipe's assessment > --- > drivers/usb/dwc3/gadget.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c > index 154f3f3e8cff..9a085eee1ae3 100644 > --- a/drivers/usb/dwc3/gadget.c > +++ b/drivers/usb/dwc3/gadget.c > @@ -2420,7 +2420,8 @@ static int dwc3_gadget_ep_reclaim_completed_trb(struct dwc3_ep *dep, > if (event->status & DEPEVT_STATUS_SHORT && !chain) > return 1; > > - if (event->status & DEPEVT_STATUS_IOC) > + if ((trb->ctrl & DWC3_TRB_CTRL_IOC) || > + (trb->ctrl & DWC3_TRB_CTRL_LST)) why the LST bit here? It wasn't there before. In fact, we never set LST in dwc3 anymore :-) -- balbi
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