Cannot adjust display brighness

[cscs]

It would be better if you provided the full output of inxi:

[HowTo] Provide System Information

This tutorial is superseded by this one. Remember all Tutorials are wiki posts that can be edited by TL2 (Trust Level 2) members and above. Welcome to Manjaro! To allow all of us helpful people on this forum TO HELP YOU, we need some basic information about your system. This probably means you described the symptoms of your problem, but now we need some more information to know where the origin of your issue is exactly. Someone else probably linked you to…