[PATCH 2/2] usb: serial: usb_wwan: Fix lackage for Quectel EG95 LTE modem support

[William Sung <william.sung@advantech.com.tw>]

As required by the USB protocol, add zero packet support for Quectel
EG95 LTE modem module.

Fixes: f815dd5cf48b ("net: usb: qmi_wwan: add support for Quectel EG95
LTE modem"

Signed-off-by: William Sung <william.sung@advantech.com.tw>
---
 drivers/usb/serial/usb_wwan.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/serial/usb_wwan.c b/drivers/usb/serial/usb_wwan.c
index 4b9845807bee..75495c939ac6 100644
--- a/drivers/usb/serial/usb_wwan.c
+++ b/drivers/usb/serial/usb_wwan.c
@@ -467,6 +467,7 @@ static struct urb *usb_wwan_setup_urb(struct usb_serial_port *port,
 	struct usb_serial *serial = port->serial;
 	struct usb_wwan_intf_private *intfdata = usb_get_serial_data(serial);
 	struct urb *urb;
+	struct usb_device_descriptor *desc = &serial->dev->descriptor;
 
 	urb = usb_alloc_urb(0, GFP_KERNEL);	/* No ISO */
 	if (!urb)
@@ -476,8 +477,15 @@ static struct urb *usb_wwan_setup_urb(struct usb_serial_port *port,
 			  usb_sndbulkpipe(serial->dev, endpoint) | dir,
 			  buf, len, callback, ctx);
 
-	if (intfdata->use_zlp && dir == USB_DIR_OUT)
-		urb->transfer_flags |= URB_ZERO_PACKET;
+	if (dir == USB_DIR_OUT) {
+		if (intfdata->use_zlp)
+			urb->transfer_flags |= URB_ZERO_PACKET;
+
+		/* Add zero packet support for Quectel EG95 */
+		if (desc->idVendor == cpu_to_le16(0x2C7C) &&
+			desc->idProduct == cpu_to_le16(0x0195))
+			urb->transfer_flags |= URB_ZERO_PACKET;
+	}
 
 	return urb;
 }
-- 
2.17.1