Description of problem:
Backlight controls doesn't work, either on Wayland and X. I really have no idea if it's drivers fault, but it's most obvious (at least for me).

Version-Release number of selected component (if applicable):
Fedora Rawhide with newest updates.

How reproducible:
Always

Steps to Reproduce:
1. Try to reduce backlight in Gnome Settings.
2.
3.

Actual results:
No effect.

Expected results:
Dimmer image from the monitor.

Additional info:
I tried
xrandr --output eDP --gamma 0.5:0.5:0.5
(and xgamma equivalent) and it works for 1-2 seconds and screen is brightened again. 

For now I'm manually setting integer value in /sys/class/backlight/radeon_bl0/brightness file, but it requires root privileges (sudo isn't enough).

I'm on radeon graphics on Acer Aspire V5 laptop.
lspci:
00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Kabini [Radeon HD 8210]

Thanks.