Comment 8 for bug 1450044

This bug do exist
- with radeon driver(s) [radeonsi in my case]
- on some AMD hardware (Kaveri [Radeon R5 Graphics])
- is well known and explained:
* https://bbs.archlinux.org/viewtopic.php?id=193130
* https://askubuntu.com/questions/662799/laptop-backlight-sets-to-maximum-at-startup-xubuntu-15-04

Either X apps only handle brightness through a hardcoded /sys path, then:
- it should be documented
- radeon driver developpers should explain why they do not use it

Either X apps can handle various brightness interfaces, then:
- they should explain how and where to configure it

I do have a working radeon_bl0 sysfs backlight interface (the only one I have), but there seem that no software using it out there.