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6.12.34 breaks CH341 driver #6941

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@986ster

Description

@986ster

Describe the bug

Using a Raspberry Pi 4B in a DeskPi Pro case, which uses /dev/ttyUSB0 for fan control and power button status amongst other things, the /dev/ttyUSB0 device is no longer being created after a kernel update from 6.12.25 to 6.12.34.

Kernel driver used for the case is CH341.

Running dmesg on the 6.12.25 kernel I get:
[ 4.294130] usbcore: registered new interface driver ch341
[ 4.294176] usbserial: USB Serial support registered for ch341-uart
[ 4.294221] ch341 3-1.4:1.0: ch341-uart converter detected
[ 4.295141] usb 3-1.4: ch341-uart converter now attached to ttyUSB0

Updating the kernel to 6.12.34 on the same device I now get:
[ 3.503324] usbcore: registered new interface driver ch341
[ 3.503368] usbserial: USB Serial support registered for ch341-uart
[ 3.503414] ch341 3-1.4:1.0: ch341-uart converter detected
[ 3.503602] ch341-uart ttyUSB0: probe with driver ch341-uart failed with error -32

This is repeatable whenever I change between these two kernel versions on the same hardware platform.

Steps to reproduce the behaviour

Update the kernel to 6.12.34 from 6.12.25 and the attached CH341 device no longer works.

Device (s)

Raspberry Pi 4 Mod. B

System

DietPi 9.14.2

vcgencmd version
Apr 30 2025 13:33:52
Copyright (c) 2012 Broadcom
version 5560078dcc8591a00f57b9068d13e5544aeef3aa (clean) (release) (start_cd)

uname -a
Good: Linux test 6.12.25+rpt-rpi-v8 #1 SMP PREEMPT Debian 1:6.12.25-1+rpt1 (2025-04-30) aarch64 GNU/Linux
Bad: Linux test 6.12.34+rpt-rpi-v8 #1 SMP PREEMPT Debian 1:6.12.34-1+rpt1~bookworm (2025-06-26) aarch64 GNU/Linux

Logs

Good (6.12.25):
[ 4.294130] usbcore: registered new interface driver ch341
[ 4.294176] usbserial: USB Serial support registered for ch341-uart
[ 4.294221] ch341 3-1.4:1.0: ch341-uart converter detected
[ 4.295141] usb 3-1.4: ch341-uart converter now attached to ttyUSB0

Bad (6.12.34):
[ 3.503324] usbcore: registered new interface driver ch341
[ 3.503368] usbserial: USB Serial support registered for ch341-uart
[ 3.503414] ch341 3-1.4:1.0: ch341-uart converter detected
[ 3.503602] ch341-uart ttyUSB0: probe with driver ch341-uart failed with error -32

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