I recently upgrade the kernel from 3.18.12 to 4.0.5, after the reboot I could no longer adjust brightness using KDE (buttons or battery monitor on the taskbar), however I can still adjust brightness by editing /sys/class/backlight/radeon_bl0/brightness. Before the kernel upgrade it was working fine, but now the battery monitor just shows brightness as 0% (even tough it actually is 100%, as shown in /sys/class/backlight/radeon_bl0/. I first thought this was a bug with the new kernel version since I hadn't changed anything else, but since I can still adjust brightness using the CLI, I now think this probably is an issue that KDE has with the new kernel version. Any suggestions on how I might solve this problem?