[PATCH 4.9 006/105] usb: gadget: udc: renesas_usb3: Fix return value of usb3_write_pipe()

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>

commit 447b8a01b84f048d93d43bfe1fcaa4fcc56595cc upstream.

This patch fixes an issue that this driver cannot go status stage
in control read when the req.zero is set to 1 and the len in
usb3_write_pipe() is set to 0. Otherwise, if we use g_ncm driver,
usb enumeration takes long time (5 seconds or more).

Fixes: 746bfe63bba3 ("usb: gadget: renesas_usb3: add support for Renesas USB3.0 peripheral controller")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/gadget/udc/renesas_usb3.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/usb/gadget/udc/renesas_usb3.c
+++ b/drivers/usb/gadget/udc/renesas_usb3.c
@@ -879,7 +879,7 @@ static int usb3_write_pipe(struct renesa
 			usb3_ep->ep.maxpacket);
 	u8 *buf = usb3_req->req.buf + usb3_req->req.actual;
 	u32 tmp = 0;
-	bool is_last;
+	bool is_last = !len ? true : false;
 
 	if (usb3_wait_pipe_status(usb3_ep, PX_STA_BUFSTS) < 0)
 		return -EBUSY;
@@ -900,7 +900,8 @@ static int usb3_write_pipe(struct renesa
 		usb3_write(usb3, tmp, fifo_reg);
 	}
 
-	is_last = usb3_is_transfer_complete(usb3_ep, usb3_req);
+	if (!is_last)
+		is_last = usb3_is_transfer_complete(usb3_ep, usb3_req);
 	/* Send the data */
 	usb3_set_px_con_send(usb3_ep, len, is_last);