[3.16.y-ckt stable] Patch "usb: cdc-acm: send zero packet for intel 7260 modem" has been added to the 3.16.y-ckt tree

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

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

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt25.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

---8<------------------------------------------------------------

>From cce88b1a13e5639686c2deb69d43eccdfe6aa3ac Mon Sep 17 00:00:00 2001
From: Lu Baolu <baolu.lu at linux.intel.com>
Date: Wed, 6 Jan 2016 15:10:04 +0800
Subject: usb: cdc-acm: send zero packet for intel 7260 modem

commit ffdb1e369a73b380fce95b05f8498d92c43842b4 upstream.

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 at intel.com>
Signed-off-by: Lu Baolu <baolu.lu at linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/usb/class/cdc-acm.c | 6 ++++++
 drivers/usb/class/cdc-acm.h | 1 +
 2 files changed, 7 insertions(+)

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 9cda90098a57..868852fd1f70 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1418,6 +1418,8 @@ 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;
 	}

@@ -1880,6 +1882,10 @@ 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 9cca2e7280bb..70d24d7e9dc5 100644
--- a/drivers/usb/class/cdc-acm.h
+++ b/drivers/usb/class/cdc-acm.h
@@ -135,3 +135,4 @@ 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)