Patch "usb: cdc_acm: Add quirk for Elatec TWN3" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

usb: cdc_acm: Add quirk for Elatec TWN3

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
usb-cdc_acm-add-quirk-for-elatec-twn3.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Maksim Salau <[email protected]>
Date: Wed, 11 Oct 2017 11:10:52 +0300
Subject: usb: cdc_acm: Add quirk for Elatec TWN3

From: Maksim Salau <[email protected]>

commit 765fb2f181cad669f2beb87842a05d8071f2be85 upstream.

Elatec TWN3 has the union descriptor on data interface. This results in failure to bind the device to the driver with the following log:
usb 1-1.2: new full speed USB device using streamplug-ehci and address 4 usb 1-1.2: New USB device found, idVendor=09d8, idProduct=0320 usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=0 usb 1-1.2: Product: RFID Device (COM)
usb 1-1.2: Manufacturer: OEM
cdc_acm 1-1.2:1.0: Zero length descriptor references
cdc_acm: probe of 1-1.2:1.0 failed with error -22

Adding the NO_UNION_NORMAL quirk for the device fixes the issue.

lsusb -v of the device:

Bus 001 Device 003: ID 09d8:0320
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00

  bDeviceClass            2 Communications
  bDeviceSubClass         0
  bDeviceProtocol         0
  bMaxPacketSize0        32
  idVendor           0x09d8
  idProduct          0x0320
  bcdDevice            3.00
  iManufacturer           1 OEM
  iProduct                2 RFID Device (COM)
  iSerial                 0
  bNumConfigurations      1

Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 67
bNumInterfaces 2
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 250mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 2 Communications
bInterfaceSubClass 2 Abstract (modem)
bInterfaceProtocol 1 AT-commands (v.25ter)
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x83 EP 3 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0020 1x 32 bytes
bInterval 2
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 2
bInterfaceClass 10 CDC Data
bInterfaceSubClass 0 Unused
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x02 EP 2 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0020 1x 32 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0020 1x 32 bytes
bInterval 0
CDC Header:
bcdCDC 1.10
CDC Call Management:
bmCapabilities 0x03
call management
use DataInterface
bDataInterface 1
CDC ACM:
bmCapabilities 0x06
sends break
line coding and serial state
CDC Union:
bMasterInterface 0
bSlaveInterface 1
Device Status: 0x0000
(Bus Powered)

---
 drivers/usb/class/cdc-acm.c |    3 +++
 1 file changed, 3 insertions(+)

@@ -1773,6 +1773,9 @@ static const struct usb_device_id acm_id
 	{ USB_DEVICE(0xfff0, 0x0100), /* DATECS FP-2000 */
 	.driver_info = NO_UNION_NORMAL, /* reports zero length descriptor */
 	},
+	{ USB_DEVICE(0x09d8, 0x0320), /* Elatec GmbH TWN3 */
+	.driver_info = NO_UNION_NORMAL, /* has misplaced union descriptor */
+	},
 
 	{ USB_DEVICE(0x2912, 0x0001), /* ATOL FPrint */
 	.driver_info = CLEAR_HALT_CONDITIONS,

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/usb-cdc_acm-add-quirk-for-elatec-twn3.patch