Ubuntu
acpi-support package

  1. Bug #76593 (andrey)
  2. Comment #38

Comment 38 for bug 76593

Chan, JP. (rewarp) wrote :

I don't know whether these patches are suppose to be automated, but I should report I just fixed my brightness key for my ASUS K401J running 12.04.

$ gksudo gedit /etc/default/grub

Find GRUB_CMDLINE_LINUX_DEFAULT=

Add "acpi_osi=Linux acpi_backlight=vendor" such that it read

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor"

Save file.

$ sudo update-grub2

My brightness keys finally work correctly 2 years after I first purchased it. Couldn't be happier.