dattasaurabh82/CH340N_linux_fix.md

## CH340N_linux_fix.md

      
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              CH340N_linux_fix.md
            
          
    Tested on Ubuntu 20, 21 earlier and they were not working.
So upgraded Ubutbu to latest 22 version.
The issue is: The built in Kernals of Ubuntu and many Linux Kernals (between )
have the CH340 drivers broken / have bugs and not fixed (from kernal 5.4.0-87 and above)
Note: I didn't try on linux kernal 5.4.0-86 my self. I though I will see how is the situation in the latest linux kernal
(as of 16/05/2022)
Instructions for Ubuntu 22.04 LTS x86_64

Get the kernel verison installed:

sudo apt-get update -y
sudo apt-get install neofetch -y
neofetch
I think it came with Kernel: 5.13.8-...
Instal latest kernel (GUI solution):

sudo add-apt-repository ppa:cappelikan/ppa
sudo apt-get update -y
sudo apt-get install mainline -y
sudo apt autoremove -y
Run mainline  and select the latest kernel (I tried, as of 16/05/2022, kernel version: 5.17.8-051708-generic)
After installation and reboot, run neofetch again and check if the latest linux kernel is loaded.
Install build tools (if not installed already):

sudo apt-get update -y
sudo apt-get install build-essential dwarves dkms make cmake -y
sudo apt autoremove -y
Install and fix CH34x drivers:

As per the guide here in sparkfun and https://github.com/juliagoda/CH341SER
git clone https://github.com/juliagoda/CH341SER
cd CH341SER
sudo make clean 

# The Makefile looks for vmlinux in a certain location (check that cat Makefile)
# we need to move that
# https://forum.proxmox.com/threads/kernel-module-not-found-when-compile-skipping-btf-generation.100974/
cp /sys/kernel/btf/vmlinux /usr/lib/modules/`uname -r`/build/

sudo make
sudo make load
lsmod | grep ch34*

# NOTE: if other/prev ch34x drivers are loaded (and you know they were not working), then you can unload them by:
sudo rmmod ch34x

# Plug and unplug your CH340 device again on the USB port
sudo dmesg

# plug un-plug your device and then verify:
ls /dev/tty*

# make it accessible
sudo usermod -a -G dialout $(whoami)
sudo chmod a+rw /dev/ttyUSB0 # if /dev/ttyUSB0 was assigned

# To unload:
sudo rmmod ch34x
# or 
sudo make unload
Disable some conflicting services.

It came out during my test, at least on my machine, a service for some external brail hardware was conflicting with the drivers. I saw that in sudo dmesg
... ch340 1-10:1.0: ch341-uart converter detected
... usb 1-10: ch341-uart converter now attached to ttyUSB0
.
.
.
... usb 1-10: usbfs: interface 0 claimed by ch341 while 'brltty' sets config #1
... ch340-uart ttyUSB0: ch341-uart converter now disconnected from ttyUSB0
It was apearing and dis-appearing.
so I tried to hunt the service as such:
sudo systemctl list-units | grep brltty
I then disabled it:
sudo systemctl stop <brl service name or other service that is interferring and not needed>
sudo systemctl disable <brl service name or other service that is interferring and not needed>
sudo systemctl mask <brl service name or other service that is interferring and not needed>

for f in /usr/lib/udev/rules.d/*brltty*.rules; do
    sudo ln -s /dev/null "/etc/udev/rules.d/$(basename "$f")"
done
sudo udevadm control --reload-rules
Future note:

Automate loading and unloading ...