The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From d2ee3ff79e6a3d4105e684021017d100524dc560 Mon Sep 17 00:00:00 2001

From: Thinh Nguyen Thinh.Nguyen@synopsys.com Date: Thu, 6 Aug 2020 19:46:29 -0700 Subject: [PATCH] usb: dwc3: gadget: Fix handling ZLP

The usb_request->zero doesn't apply for isoc. Also, if we prepare a 0-length (ZLP) TRB for the OUT direction, we need to prepare an extra TRB to pad up to the MPS alignment. Use the same bounce buffer for the ZLP TRB and the extra pad TRB.

Cc: stable@vger.kernel.org # v4.5+ Fixes: d6e5a549cc4d ("usb: dwc3: simplify ZLP handling") Fixes: 04c03d10e507 ("usb: dwc3: gadget: handle request->zero") Signed-off-by: Thinh Nguyen thinhn@synopsys.com Signed-off-by: Felipe Balbi balbi@kernel.org

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index f9231253cbed..df603a817a98 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -1199,6 +1199,7 @@ static void dwc3_prepare_one_trb_linear(struct dwc3_ep *dep, req->request.no_interrupt, req->request.is_last); } else if (req->request.zero && req->request.length && + !usb_endpoint_xfer_isoc(dep->endpoint.desc) && (IS_ALIGNED(req->request.length, maxp))) { struct dwc3 *dwc = dep->dwc; struct dwc3_trb *trb; @@ -1208,14 +1209,25 @@ static void dwc3_prepare_one_trb_linear(struct dwc3_ep *dep, /* prepare normal TRB */ dwc3_prepare_one_trb(dep, req, length, true, 0);

- /* Now prepare one extra TRB to handle ZLP */ + /* Prepare one extra TRB to handle ZLP */ trb = &dep->trb_pool[dep->trb_enqueue]; req->num_trbs++; __dwc3_prepare_one_trb(dep, trb, dwc->bounce_addr, 0, - false, 1, req->request.stream_id, + !req->direction, 1, req->request.stream_id, req->request.short_not_ok, req->request.no_interrupt, req->request.is_last); + + /* Prepare one more TRB to handle MPS alignment for OUT */ + if (!req->direction) { + trb = &dep->trb_pool[dep->trb_enqueue]; + req->num_trbs++; + __dwc3_prepare_one_trb(dep, trb, dwc->bounce_addr, maxp, + false, 1, req->request.stream_id, + req->request.short_not_ok, + req->request.no_interrupt, + req->request.is_last); + } } else { dwc3_prepare_one_trb(dep, req, length, false, 0); } @@ -2690,8 +2702,17 @@ static int dwc3_gadget_ep_cleanup_completed_request(struct dwc3_ep *dep, status);

if (req->needs_extra_trb) { + unsigned int maxp = usb_endpoint_maxp(dep->endpoint.desc); + ret = dwc3_gadget_ep_reclaim_trb_linear(dep, req, event, status); + + /* Reclaim MPS padding TRB for ZLP */ + if (!req->direction && req->request.zero && req->request.length && + !usb_endpoint_xfer_isoc(dep->endpoint.desc) && + (IS_ALIGNED(req->request.length, maxp))) + ret = dwc3_gadget_ep_reclaim_trb_linear(dep, req, event, status); + req->needs_extra_trb = false; }