Hardware brightness buttons 🔅 🔆
Before Ubuntu LTS 16.04
Under (X)Ubuntu 14.04 LTS, brightness control on my Panasonic Toughbook CF-52 used to work fine by adding
acpi_osi=Linux to the
GRUB_CMDLINE_LINUX_DEFAULT= line in
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux"
$ sudo update-grub
after editing and before rebooting.
Since Ubuntu LTS 16.04
However, above solution stopped working after upgrading to (X)Ubuntu LTS 16.04.
This appears to be typical for laptops with integrated Intel video graphics.
To find out if you have integrated Intel video graphics, enter the following command:
$ ls /sys/class/backlight/
intel_backlight should be mentioned, most probably in addition to an OEM name like for example
If this is the case, proceed with creating the following file
$ sudo nano /usr/share/X11/xorg.conf.d/20-intel.conf
containing the following lines:
Option "Backlight" "intel_backlight"
Reboot, and enjoy your backlight buttons! [Source]
Finer-grained brightness control
If brightness control happens to be too coarse, then make this additional adjustment.