brlttty claiming CH341 usbtty device blocking access

[beattie]

While this problem seems to have been fixed for FTDI and CP210 based devices CH340/CH341 based (and possibly other USB serial adapters) are unusable except by brltty.

Workaround: disable brltty
sudo systemctl stop brltty-udev.service
sudo systemctl mask brltty-udev.service
sudo systemctl stop brltty.service
sudo systemctl disable brltty.service

[139099.253351] usb 1-2.1.2: new full-speed USB device number 17 using xhci_hcd
[139099.370766] usb 1-2.1.2: New USB device found, idVendor=1a86, idProduct=7523, bcdDevice= 2.63
[139099.370777] usb 1-2.1.2: New USB device strings: Mfr=0, Product=2, SerialNumber=0
[139099.370782] usb 1-2.1.2: Product: USB2.0-Serial
[139099.414885] ch341 1-2.1.2:1.0: ch341-uart converter detected
[139099.429265] usb 1-2.1.2: ch341-uart converter now attached to ttyUSB0
[139100.045076] input: BRLTTY 6.4 Linux Screen Driver Keyboard as /devices/virtual/input/input24
[139100.782817] usb 1-2.1.2: usbfs: interface 0 claimed by ch341 while 'brltty' sets config #1
[139100.786100] ch341-uart ttyUSB0: ch341-uart converter now disconnected from ttyUSB0
[139100.786136] ch341 1-2.1.2:1.0: device disconnected
[143917.740171] usb 1-2.1.2: USB disconnect, device number 17

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=22.04
DISTRIB_CODENAME=jammy
DISTRIB_DESCRIPTION="Ubuntu 22.04.1 LTS"

ProblemType: BugDistroRelease: Ubuntu 22.04
Package: brltty 6.4-4ubuntu3
ProcVersionSignature: Ubuntu 5.15.0-47.51-generic 5.15.46
Uname: Linux 5.15.0-47-generic x86_64
ApportVersion: 2.20.11-0ubuntu82.1
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: MATE
Date: Mon Sep 19 12:01:21 2022
InstallationDate: Installed on 2022-08-23 (27 days ago)
InstallationMedia: Ubuntu-MATE 22.04.1 LTS "Jammy Jellyfish" - Release amd64 (20220809.1)
ProcEnviron:
 LANGUAGE=en_US
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bashSourcePackage: brltty
UpgradeStatus: No upgrade log present (probably fresh install)

[Samuel thibault (samuel-thibault)]

Hello,

beattie, le lun. 19 sept. 2022 19:07:54 -0000, a ecrit:
> [139099.370766] usb 1-2.1.2: New USB device found, idVendor=1a86, idProduct=7523, bcdDevice= 2.63

Could you run

lsusb -v

so we get more information on how the generic bridge announces itself?

Samuel

[Samuel thibault (samuel-thibault)]

Ok. That'd be tricky to filter. Fortunately with brltty 6.5 such generic entries are kept apart so that they can be packaged separately.

[beattie (beattie)]

is there a work around?

[Samuel thibault (samuel-thibault)]

The simple workaround is to remove the package, or remove the entry from the udev file.

[beattie (beattie)]

can't find anything in the udev, removing brltty breaks some dependencies. Braille is good an all but I think somebody did not do their testing.

[Samuel thibault (samuel-thibault)]

Hello,

beattie, le mar. 20 sept. 2022 15:21:36 -0000, a ecrit:
> can't find anything in the udev,

That's be in ./lib/udev/rules.d/85-brltty.rules, this line:

ENV{PRODUCT}=="1a86/7523/*", ENV{BRLTTY_BRAILLE_DRIVER}="bm", GOTO="brltty_usb_run"

> I think somebody did not do their testing.

Not many people have a CH340/CH341-based adapter to notice the issue.

Samuel

[beattie (beattie)]

no such file as *brltty.rules" in my udev. What I did that seems to work is:

sudo systemctl stop brltty-udev.service
sudo systemctl mask brltty-udev.service
sudo systemctl stop brltty.service
sudo systemctl disable brltty.service

Not sure if this is best or even a good idea but at least it stops brltty from stealing my serial port. Since I don't use brltty it does not hurt me that brltty can't coexist with my CH340 serial port.

[storepeter (kzqdnsw4i20a5pz947ygrr-peter)]

Glad I found this bug report.

The USB-id 1a86/7523 is used by CH340 based USB-serial ports,
which is what is used on Chinese Arduino and many rs485 USB adapters,
and a lot of other stuff, certainly much more general use than just brltty

I would argue that there are plenty more people using one of the above devices,
but I guess their reaction - like mine has been just to stay on ubuntu-20.04
until the issue is resolved

I recomend removing the entry from /lib/udev/rules.d/85-brltty.rules

Now I found this bug report this is what I did, and should be good until
the system decides to update that file and put it back again.

StorePeter

[Paul Gevers (paul-climbing)]

Hi,

On 28-10-2022 16:43, storepeter wrote:
> I recomend removing the entry from /lib/udev/rules.d/85-brltty.rules
>
> Now I found this bug report this is what I did, and should be good until
> the system decides to update that file and put it back again.

I *think* that if you copy your modified file to /etc/udev/rules.d
instead, it's saved over system updates.

Paul

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[JP Meijers (jpm)]

This bug affects me while trying to program an ESP32 device from Arduino. Uninstalling brltty solves it.

[Julian Andres Klode (juliank)]

This has been fixed in mantic, and the following needs to be cherry-picked to 22.04:

 # Device: 1A86:7523
+# Generic Identifier
+# Vendor: Jiangsu QinHeng, Ltd.
+# Product: CH341 USB Bridge Controller
 # Baum [NLS eReader Zoomax (20 cells)]
-ENV{PRODUCT}=="1a86/7523/*", ENV{BRLTTY_BRAILLE_DRIVER}="bm", GOTO="brltty_usb_run"
+ENV{PRODUCT}=="1a86/7523/*", ATTRS{idVendor}=="1a40", ATTRS{idProduct}=="0101", ENV{BRLTTY_BRAILLE_DRIVER}="bm", GOTO="brltty_usb_run"

This bug is similar to bug 1958224.

[Julian Andres Klode (juliank)]

Triaging this as high matching bug 1958224.