[PATCH 4.19 122/125] usb: dwc3: gadget: Handle ZLP for sg requests

[Greg Kroah-Hartman]

From: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>

[ Upstream commit bc9a2e226ea95e1699f7590845554de095308b75 ]

Currently dwc3 doesn't handle usb_request->zero for SG requests. This
change checks and prepares extra TRBs for the ZLP for SG requests.

Cc: <stable@xxxxxxxxxxxxxxx> # v4.5+
Fixes: 04c03d10e507 ("usb: dwc3: gadget: handle request->zero")
Signed-off-by: Thinh Nguyen <thinhn@xxxxxxxxxxxx>
Signed-off-by: Felipe Balbi <balbi@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/usb/dwc3/gadget.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 9f6b430773000..7bf2573dd459e 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1104,6 +1104,35 @@ static void dwc3_prepare_one_trb_sg(struct dwc3_ep *dep,
 					req->request.stream_id,
 					req->request.short_not_ok,
 					req->request.no_interrupt);
+		} else if (req->request.zero && req->request.length &&
+			   !usb_endpoint_xfer_isoc(dep->endpoint.desc) &&
+			   !rem && !chain) {
+			struct dwc3	*dwc = dep->dwc;
+			struct dwc3_trb	*trb;
+
+			req->needs_extra_trb = true;
+
+			/* Prepare normal TRB */
+			dwc3_prepare_one_trb(dep, req, trb_length, true, i);
+
+			/* 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,
+					       !req->direction, 1,
+					       req->request.stream_id,
+					       req->request.short_not_ok,
+					       req->request.no_interrupt);
+
+			/* Prepare one more TRB to handle MPS alignment */
+			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);
+			}
 		} else {
 			dwc3_prepare_one_trb(dep, req, trb_length, chain, i);
 		}
-- 
2.25.1