Hi, Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> writes: >> 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 :-) > > Just a note: right now, it may be fine for non-stream endpoints to not > set the LST bit in the TRBs. For streams, we need to set this bit so the > controller know to allocate resource for different transfers of > different streams. It may be fine now if you think that it should be > added later when more fixes for streams are added, but I think it > doesn't hurt checking it now either. Indeed. Let's keep this version as is if we will need LST for Streams anyway. Sorry for the noise. -- balbi
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