From: Tejas Joglekar <tejas.joglekar@synopsys.com>
Date: Tue, 22 Jan 2019 07:56:51 +0000 (+0530)
Subject: usb: dwc3: gadget: Handle 0 xfer length for OUT EP
X-Git-Tag: v5.0-rc6~24^2~1^2~4
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=1e19cdc8060227b0802bda6bc0bd22b23679ba32;p=linux.git

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

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: c6267a51639b ("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
index bed2ff42780b..6c9b76bcc2e1 100644
--- 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;