usb: dwc3: gadget: Handle 0 xfer length for OUT EP

Tejas Joglekar · Felipe Balbi · commit 1e19cdc80602 · 2019-01-28T15:27:07.000+02:00
For OUT endpoints, zero-length transfers require MaxPacketSize buffer as per the DWC_usb3 programming guide 3.30a section 4.2.3.3. This patch fixes this by explicitly checking zero length transfer to correctly pad up to MaxPacketSize. Fixes: c6267a5 ("usb: dwc3: gadget: align transfers to wMaxPacketSize") Cc: stable@vger.kernel.org Signed-off-by: Tejas Joglekar <joglekar@synopsys.com> Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
@@ -1119,7 +1119,7 @@ static void dwc3_prepare_one_trb_linear(struct dwc3_ep *dep,
 	unsigned int maxp = usb_endpoint_maxp(dep->endpoint.desc);
 	unsigned int rem = length % maxp;
 
-	if (rem && usb_endpoint_dir_out(dep->endpoint.desc)) {
+	if ((!length || rem) && usb_endpoint_dir_out(dep->endpoint.desc)) {
 		struct dwc3	*dwc = dep->dwc;
 		struct dwc3_trb	*trb;
 
