I really can't believe I found a solution for this after such a long time trying (way before I posted here...)
First, go to Settings > Software and Updates > Additional Drivers (this last one is a tab). Choose the official Nvidia driver (the latest and tested one).
Second, go to your terminal window and run sudo nvidia-xconfig
. It will generate a xorg.conf
file for you.
Third, go to that file and do as mentioned here (quote below)
This will open your X server configuration (after prompting for your password). You should see a section titled "Device" that looks as follows:
Section "Device"
Identifier "Default Device"
Driver "nvidia"
Option "NoLogo" "True"
EndSection
Append a line so it appears like this:
Section "Device"
Identifier "Default Device"
Driver "nvidia"
Option "NoLogo" "True"
Option "RegistryDwords" "EnableBrightnessControl=1"
EndSection
Lastly, restart you x server as mentioned here (quote below for lightdm. For the others is similar).
sudo restart lightdm
EDIT:
I just reused this method, and it worked again. For documentation purposes, my xorg.conf
generated by sudo nvidia-xconfig
was like this before including the "RegistryDwords" line:
Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
EndSection
UPDATE:
For those of you having brightness problems in Debian (I tested for Debian 8), the solution provided above also works, but first instead of going to the Settings > Software and Updates > Additional Drivers you need to follow the 4 steps mentioned here.
EDIT Mar 31 2016:
For Ubuntu 14.04.4, it is also necessary to do what Crowell says in his answer.