usb: dwc3: ep0: correct cache sync issue in case of ep0_bounced

In case of ep0 out, if length is not aligned to maxpacket size then we use
dwc->ep_bounce_addr for dma transfer and not request->dma. Since, we have
alreday done memcpy from dwc->ep0_bounce to request->buf, so we do not need to
issue cache sync function. In fact, cache sync function will bring wrong data
in request->buf from request->dma in this scenario.

So, cache sync function must not be executed in case of ep0 bounced.

Cc: <stable@vger.kernel.org> # v3.4 v3.5
Signed-off-by: Pratyush Anand <pratyush.anand@st.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/ep0.c

@@ -720,7 +720,6 @@ static void dwc3_ep0_complete_data(struct dwc3 *dwc,
 		transferred = min_t(u32, ur->length,
 				transfer_size - length);
 		memcpy(ur->buf, dwc->ep0_bounce, transferred);
-		dwc->ep0_bounced = false;
 	} else {
 		transferred = ur->length - length;
 	}

drivers/usb/dwc3/gadget.c

@@ -263,6 +263,9 @@ void dwc3_gadget_giveback(struct dwc3_ep *dep, struct dwc3_request *req,
 	if (req->request.status == -EINPROGRESS)
 		req->request.status = status;
 
+	if (dwc->ep0_bounced && dep->number == 0)
+		dwc->ep0_bounced = false;
+	else
 		usb_gadget_unmap_request(&dwc->gadget, &req->request,
 				req->direction);