usb: cdc-acm: send zero packet for intel 7260 modem

For Intel 7260 modem, it is needed for host side to send zero
packet if the BULK OUT size is equal to USB endpoint max packet
length. Otherwise, modem side may still wait for more data and
cannot give response to host side.

Signed-off-by: Konrad Leszczynski <konrad.leszczynski@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 7 insertions, 0 deletions

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 8cd193bbd044..e4c70dce3e7c 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1405,6 +1405,8 @@ made_compressed_probe:
                                 usb_sndbulkpipe(usb_dev, epwrite->bEndpointAddress),
                                 NULL, acm->writesize, acm_write_bulk, snd);
                 snd->urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+                if (quirks & SEND_ZERO_PACKET)
+                        snd->urb->transfer_flags |= URB_ZERO_PACKET;
                 snd->instance = acm;
         }
 
@@ -1862,6 +1864,10 @@ static const struct usb_device_id acm_ids[] = {
         { USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_ACM,
                 USB_CDC_ACM_PROTO_AT_CDMA) },
 
+        { USB_DEVICE(0x1519, 0x0452), /* Intel 7260 modem */
+        .driver_info = SEND_ZERO_PACKET,
+        },
+
         { }
 };
 
diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h
index dd9af38e7cda..ccfaba9ab4e4 100644
--- a/drivers/usb/class/cdc-acm.h
+++ b/drivers/usb/class/cdc-acm.h
@@ -134,3 +134,4 @@ struct acm {
 #define IGNORE_DEVICE                   BIT(5)
 #define QUIRK_CONTROL_LINE_STATE        BIT(6)
 #define CLEAR_HALT_CONDITIONS           BIT(7)
+#define SEND_ZERO_PACKET                BIT(8)