[PATCH 4.9 047/120] USB: serial: ch341: fix resume after reset

[Greg Kroah-Hartman]

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

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

From: Johan Hovold <johan@xxxxxxxxxx>

commit ce5e292828117d1b71cbd3edf9e9137cf31acd30 upstream.

Fix reset-resume handling which failed to resubmit the read and
interrupt URBs, thereby leaving a port that was open before suspend in a
broken state until closed and reopened.

Fixes: 1ded7ea47b88 ("USB: ch341 serial: fix port number changed after resume")
Fixes: 2bfd1c96a9fb ("USB: serial: ch341: remove reset_resume callback")
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/serial/ch341.c |   17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -538,14 +538,23 @@ static int ch341_tiocmget(struct tty_str
 
 static int ch341_reset_resume(struct usb_serial *serial)
 {
-	struct ch341_private *priv;
-
-	priv = usb_get_serial_port_data(serial->port[0]);
+	struct usb_serial_port *port = serial->port[0];
+	struct ch341_private *priv = usb_get_serial_port_data(port);
+	int ret;
 
 	/* reconfigure ch341 serial port after bus-reset */
 	ch341_configure(serial->dev, priv);
 
-	return 0;
+	if (tty_port_initialized(&port->port)) {
+		ret = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO);
+		if (ret) {
+			dev_err(&port->dev, "failed to submit interrupt urb: %d\n",
+				ret);
+			return ret;
+		}
+	}
+
+	return usb_serial_generic_resume(serial);
 }
 
 static struct usb_serial_driver ch341_device = {