Just add the acpi_backlight=vendor (grub) and put in /etc/X11/xorg.conf.d/80-backlight.conf :
Section "Device" Identifier "Intel Graphics" Driver "intel" Option "Backlight" "intel_backlight" # use your backlight that works here EndSection
ArchWiki: https://wiki.archlinux.org/index.php/Backlight
Kernel 3.12.6-1 (x86_64) under Archlinux, xorg-server 1.14.5-2
Just add the acpi_backlight= vendor (grub) and put in /etc/X11/ xorg.conf. d/80-backlight. conf :
Section "Device"
Identifier "Intel Graphics"
Driver "intel"
Option "Backlight" "intel_backlight" # use your backlight that works here
EndSection
ArchWiki: /wiki.archlinux .org/index. php/Backlight
https:/
Kernel 3.12.6-1 (x86_64) under Archlinux, xorg-server 1.14.5-2