[PATCH V3 1/1] usb: serial: option: add ZLP support for 0x1bc7/0x9010

[Daniele Palmas <dnlplm@gmail.com>]

Telit FN980 flashing device 0x1bc7/0x9010 requires zero packet
to be sent if out data size is equal to the endpoint max size.

Signed-off-by: Daniele Palmas <dnlplm@gmail.com>
---
V3: moved zlp setting to urb setup
V2: removed transfer_length calculations
---
 drivers/usb/serial/option.c   | 8 ++++++++
 drivers/usb/serial/usb-wwan.h | 1 +
 drivers/usb/serial/usb_wwan.c | 3 +++
 3 files changed, 12 insertions(+)

diff --git a/drivers/usb/serial/option.c b/drivers/usb/serial/option.c
index e9491d400a24..c13e063cb399 100644
--- a/drivers/usb/serial/option.c
+++ b/drivers/usb/serial/option.c
@@ -567,6 +567,9 @@ static void option_instat_callback(struct urb *urb);
 /* Interface must have two endpoints */
 #define NUMEP2		BIT(16)
 
+/* Device needs ZLP */
+#define ZLP		BIT(17)
+
 
 static const struct usb_device_id option_ids[] = {
 	{ USB_DEVICE(OPTION_VENDOR_ID, OPTION_PRODUCT_COLT) },
@@ -1196,6 +1199,8 @@ static const struct usb_device_id option_ids[] = {
 	  .driver_info = NCTRL(0) | RSVD(1) },
 	{ USB_DEVICE_INTERFACE_CLASS(TELIT_VENDOR_ID, 0x1901, 0xff),	/* Telit LN940 (MBIM) */
 	  .driver_info = NCTRL(0) },
+	{ USB_DEVICE(TELIT_VENDOR_ID, 0x9010),				/* Telit SBL FN980 flashing device */
+	  .driver_info = NCTRL(0) | ZLP },
 	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, ZTE_PRODUCT_MF622, 0xff, 0xff, 0xff) }, /* ZTE WCDMA products */
 	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, 0x0002, 0xff, 0xff, 0xff),
 	  .driver_info = RSVD(1) },
@@ -2097,6 +2102,9 @@ static int option_attach(struct usb_serial *serial)
 	if (!(device_flags & NCTRL(iface_desc->bInterfaceNumber)))
 		data->use_send_setup = 1;
 
+	if (device_flags & ZLP)
+		data->use_zlp = 1;
+
 	spin_lock_init(&data->susp_lock);
 
 	usb_set_serial_data(serial, data);
diff --git a/drivers/usb/serial/usb-wwan.h b/drivers/usb/serial/usb-wwan.h
index 1c120eaf4091..934e9361cf6b 100644
--- a/drivers/usb/serial/usb-wwan.h
+++ b/drivers/usb/serial/usb-wwan.h
@@ -38,6 +38,7 @@ struct usb_wwan_intf_private {
 	spinlock_t susp_lock;
 	unsigned int suspended:1;
 	unsigned int use_send_setup:1;
+	unsigned int use_zlp:1;
 	int in_flight;
 	unsigned int open_ports;
 	void *private;
diff --git a/drivers/usb/serial/usb_wwan.c b/drivers/usb/serial/usb_wwan.c
index 7e855c87e4f7..66325aaee149 100644
--- a/drivers/usb/serial/usb_wwan.c
+++ b/drivers/usb/serial/usb_wwan.c
@@ -462,6 +462,7 @@ static struct urb *usb_wwan_setup_urb(struct usb_serial_port *port,
 {
 	struct usb_serial *serial = port->serial;
 	struct urb *urb;
+	struct usb_wwan_intf_private *intfdata = usb_get_serial_data(serial);
 
 	urb = usb_alloc_urb(0, GFP_KERNEL);	/* No ISO */
 	if (!urb)
@@ -470,6 +471,8 @@ static struct urb *usb_wwan_setup_urb(struct usb_serial_port *port,
 	usb_fill_bulk_urb(urb, serial->dev,
 			  usb_sndbulkpipe(serial->dev, endpoint) | dir,
 			  buf, len, callback, ctx);
+	if (dir == USB_DIR_OUT && intfdata->use_zlp)
+		urb->transfer_flags |= URB_ZERO_PACKET;
 
 	return urb;
 }
-- 
2.17.1