I have a Lenovo Z50 laptop with ubuntu 14.04 installed.
The brightness control buttons are not working.
Searched net for this and found solution.
Here is the fix:
Open a terminal and create the following configuration file, if it does not exist:
sudo touch /usr/share/X11/xorg.conf.d/20-intel.conf
Now we need to edit this file. You can use any editor be it a terminal one or graphical.
sudo gedit /usr/share/X11/xorg.conf.d/20-intel.conf
Add the following lines to this file:
Section "Device" Identifier "card0" Driver "intel" Option "Backlight" "intel_backlight" BusID "PCI:0:2:0" EndSection
Save it. Log out and log in back.
It is working fine now.
Thanks for the itsfoss team and stackoeverflow contributors.