The laptop brightness key provide easy management of brightness options from the keyboard. This is done with or without the combination of the FN key, depending upon your manufacturer. Unfortunately, some Ubuntu 10.10 and 11.04 users using NVIDIA graphic cards are having problem with using this key and are unable to change the screen brightness from their keyboard. A solution to this problem is to edit dit xorg.conf. Below is a procedure which can make your laptop’s brightness button functional again for your Ubuntu OS (NVIDIA users only).
Note: Before making these changes, it is adviced to backup your system to revert back to your former settings in case of any possible issues. The below mentioned practice is not advised for non-NVIDIA users.
Open Terminal and enter below command to open the xorg.conf file for editing:
sudo gedit /etc/X11/xorg.conf
Once the file opens, find Section “Device” and add –> Option “RegistryDwords” “EnableBrightnessControl=1” (as shown below in bold line), and hit Ctrl+S to save it.
Section “Device” Identifier “Default Device” Option “NoLogo” “True” Option “RegistryDwords” “EnableBrightnessControl=1″ EndSection
This tip was posted by Guskuma in the Ubuntu Forum and has been successful for NVIDIA users with different kinds of laptop models.