My brightness function key controls work after setting grub boot parameter to "acpi_osi=" but using them I cannot adjust the brightness higher than around 70% (there is empty bar left over and I can't adjust higher) unless I go to Brightness & Lock settings manually than I can use the slider to adjust it higher... I primarily use intel_backlight to adjust my backlight and I am running Linux kernel 3.14.1 on Ubuntu 14.04 LTS on an ASUS X550LA Laptop when I try: cd /sys/class/backlight/intel_backlight cat max_brightness 937 cat brightness 811 It seems that I can only adjust to a maximum of 811 using the fn brightness controls If I instead do cd /sys/class/backlight/acpi_video0 cat max_brightness 10 cat brightness 4 cat actual_brightness 10 With the FN keys actual_brightness is not equal to the value returned from brightness on acip_video0 (which is always 4) but on intel_backlight actual_brightness = brightness The adjustment problem seemingly arises because both intel_backlight and acpi_video0 are trying to adjust brightness