Cannot adjust screen brightness 20.04 AMD APU

Using a Lenovo Slim 7 with 4700u and vega 8 processor. Have tried just about every distro even arch and I cannot get control the brightness. My screen just stays bright non-stop. I have edited the grub file... nothing. I have messed around with the udev rules... nothing. I have tried countless applications and nothing works. Any help would be greatly appreciated.

Solution 1:

I have the same laptop as yours and to fix the brightness problem you can upgrade to latest kernel (I use 5.8) by using various kernel updater such as (https://github.com/bkw777/mainline or https://github.com/pimlie/ubuntu-mainline-kernel.sh)

Example instruction using https://github.com/pimlie/ubuntu-mainline-kernel.sh

sudo apt install wget
wget https://raw.githubusercontent.com/pimlie/ubuntu-mainline-kernel.sh/master/ubuntu-mainline-kernel.sh
chmod +x ubuntu-mainline-kernel.sh
sudo mv ubuntu-mainline-kernel.sh /usr/local/bin/

sudo ubuntu-mainline-kernel.sh -i

Solution 2:

I'm using HP elitebook 845 G7 with the same Ryzen 4700u mobile processor and suffering from the same "Back light control issue".

I still doesn't work after trying a lot of method like:

1. append "acpi=vedor" in /etc/default/grub
2. update gnome
3. update to the latest kernel
4. try mesa gpu driver

Finally, I found a solution from another Linux Distro community Mini. Power reset your computer and it fix!

• Power reset on My HP laptop is
  1. Turn off the laptop
  2. Unplug all cords
  3. Press & hold power button for 15 seconds You may give it a try!

Note that I'm dual boot user on the same SSD drive, and it will fail again after booting into windows.