Patch "USB: cdc_acm: Ignore Infineon Flash Loader utility" has been added to the 4.1-stable tree

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

USB: cdc_acm: Ignore Infineon Flash Loader utility

to the 4.1-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-ignore-infineon-flash-loader-utility.patch
and it can be found in the queue-4.1 subdirectory.

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

From: Jonas Jonsson <[email protected]>
Date: Sun, 22 Nov 2015 11:47:17 +0100
Subject: USB: cdc_acm: Ignore Infineon Flash Loader utility

From: Jonas Jonsson <[email protected]>

commit f33a7f72e5fc033daccbb8d4753d7c5c41a4d67b upstream.

Some modems, such as the Telit UE910, are using an Infineon Flash Loader utility. It has two interfaces, 2/2/0 (Abstract Modem) and 10/0/0 (CDC Data). The latter can be used as a serial interface to upgrade the firmware of the modem. However, that isn't possible when the cdc-acm driver takes control of the device.

The following is an explanation of the behaviour by Daniele Palmas during discussion on linux-usb.

"This is what happens when the device is turned on (without modifying the drivers):

[155492.352031] usb 1-3: new high-speed USB device number 27 using ehci-pci
[155492.485429] usb 1-3: config 1 interface 0 altsetting 0 endpoint 0x81 has an invalid bInterval 255, changing to 11
[155492.485436] usb 1-3: New USB device found, idVendor=058b, idProduct=0041
[155492.485439] usb 1-3: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[155492.485952] cdc_acm 1-3:1.0: ttyACM0: USB ACM device

This is the flashing device that is caught by the cdc-acm driver. Once the ttyACM appears, the application starts sending a magic string (simple write on the file descriptor) to keep the device in flashing mode. If this magic string is not properly received in a certain time interval, the modem goes on in normal operative mode:

[155493.748094] usb 1-3: USB disconnect, device number 27
[155494.916025] usb 1-3: new high-speed USB device number 28 using ehci-pci
[155495.059978] usb 1-3: New USB device found, idVendor=1bc7, idProduct=0021
[155495.059983] usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[155495.059986] usb 1-3: Product: 6 CDC-ACM + 1 CDC-ECM
[155495.059989] usb 1-3: Manufacturer: Telit
[155495.059992] usb 1-3: SerialNumber: 359658044004697
[155495.138958] cdc_acm 1-3:1.0: ttyACM0: USB ACM device
[155495.140832] cdc_acm 1-3:1.2: ttyACM1: USB ACM device
[155495.142827] cdc_acm 1-3:1.4: ttyACM2: USB ACM device
[155495.144462] cdc_acm 1-3:1.6: ttyACM3: USB ACM device
[155495.145967] cdc_acm 1-3:1.8: ttyACM4: USB ACM device
[155495.147588] cdc_acm 1-3:1.10: ttyACM5: USB ACM device
[155495.154322] cdc_ether 1-3:1.12 wwan0: register 'cdc_ether' at usb-0000:00:1a.7-3, Mobile Broadband Network Device, 00:00:11:12:13:14

Using the cdc-acm driver, the string, though being sent in the same way than using the usb-serial-simple driver (I can confirm that the data is passing properly since I used an hw usb sniffer), does not make the device to stay in flashing mode."

---
 drivers/usb/class/cdc-acm.c |    5 +++++
 1 file changed, 5 insertions(+)

@@ -1848,6 +1848,11 @@ static const struct usb_device_id acm_id
 	},
 #endif
 
+	/* Exclude Infineon Flash Loader utility */
+	{ USB_DEVICE(0x058b, 0x0041),
+	.driver_info = IGNORE_DEVICE,
+	},
+
 	/* control interfaces without any protocol set */
 	{ USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_ACM,
 		USB_CDC_PROTO_NONE) },

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

queue-4.1/usb-serial-another-infineon-flash-loader-usb-id.patch queue-4.1/usb-cdc_acm-ignore-infineon-flash-loader-utility.patch