I am restating my question as posed on my previous post. I cannot change the brightness on my machine.

I have a Lenovo Ideapad (330S-15ARR - Type 81FB) running Ubuntu 18.04.4 with an AMD Ryzen 5 2500u with radeon vega mobile gfx × 8.

When running

ls /sys/class/backlight

the result is


Has anyone else had a similar issue and found a resolution?

Apologies about my previous question not being detailed enough, I have been absent from tech for some time now.


I had similar issues with a toshiba laptop. This may help:

Make a backup copy of any files that are changed.

Edit the file /etc/default/grub.

Find the line GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

Add acpi_backlight=vendor so the line is now:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

After file is edited and saved run the command:

sudo update-grub

Reboot to see if changes have helped.

If there seems to be no change then here are some similar solutions than may lead to an answer for you.

Cannot change backlight brightness Ubuntu 14.04

Function Keys Do Not work (Brightness & Sound) Ubuntu 16.04


Don't know if this is still relevant for the questioner but maybe some people (like me) will encounter the same problem, so here is what helped on my system:

Update the kernel to a higher version(e.g. 5.8.17 by using a tool like https://github.com/pimlie/ubuntu-mainline-kernel.sh)

Trying to change the value GRUB_CMDLINE_LINUX_DEFAULT= to a variety of different alternatives almost had no effect at all for me.

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