Brightness Problem in Ubuntu 12.04 [ Solved ] - Best Solution

Here is the best solution that can increase or decrease the brightness of the PC with Ubuntu - using the function and brightness button. Just follow the following steps:

Open terminal (Clt+Alt+T)  and run the command given below:

sudo gedit /etc/default/grub

Now the new window opens and you will see the lines given below:

 GRUB_CMDLINE_LINUX_DEFAULT="quite_splice"

GRUB_CMDLINE_LINUX_DEFAULT="" 

Now you have to change the lines above by the command lines given below:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm=force acpi_backlight=vendor"

Then save the window and Update the grub from the terminal using :

sudo update-grub

Now you can Increase or decrease the brightness in PC with Latest Ubuntu in it.
Enjoy!