usb: dwc3: gadget: Handle ZLP for sg requests

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@vger.kernel.org> # v4.5+
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 df603a817a98fae3a553786e7e479522ccc54ee7..c2a0f64f8d1e12e7b949ae8b6978a3a02aee5338 100644 (file)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1143,6 +1143,37 @@ static void dwc3_prepare_one_trb_sg(struct dwc3_ep *dep,
                                        req->request.short_not_ok,
                                        req->request.no_interrupt,
                                        req->request.is_last);
+               } 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,
+                                              req->request.is_last);
+
+                       /* 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,
+                                                      req->request.is_last);
+                       }
                } else {
                        dwc3_prepare_one_trb(dep, req, trb_length, chain, i);
                }