4.20-stable review patch. If anyone has any objections, please let me know.
------------------
From: Tejas Joglekar <tejas.joglekar@xxxxxxxxxxxx>
commit 1e19cdc8060227b0802bda6bc0bd22b23679ba32 upstream.
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@xxxxxxxxxxxxxxx
Signed-off-by: Tejas Joglekar <joglekar@xxxxxxxxxxxx>
Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/dwc3/gadget.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1119,7 +1119,7 @@ static void dwc3_prepare_one_trb_linear(
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;
