sudo gedit /etc/X11/xorg.conf

ls /sys/class/backlight/

sudo touch /usr/share/X11/xorg.conf.d/20-intel.conf

sudo gedit /usr/share/X11/xorg.conf.d/20-intel.conf

Section "Device"
    Identifier  "card0"
    Driver      "intel"
    Option      "Backlight"  "intel_backlight"
    BusID       "PCI:0:2:0"
EndSection

gksu gedit /usr/share/X11/xorg.conf.d/20-nvidia.conf

Section "Device"
   Identifier     "Device0"
   Driver         "nvidia"
   VendorName     "NVIDIA Corporation"
   BoardName      "NVS 5400M"
EndSection

Option        "RegistryDwords" "EnableBrightnessControl=1"

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "NVS 5400M"
    Option         "RegistryDwords" "EnableBrightnessControl=1"
EndSection