Can't adjust brightness on a Sony Vaio T13 ultrabook

Question

I recently installed Ubuntu 12.04 alongside Windows 7 in a Vaio T13 ultrabook.

I cannot use the the Fn+F4 or Fn+F5 to change the brightness. The bubble appears indicating that brightness is being changed but with no visual impact on the screen.

I've tried many solutions involving the manipulation of the /etc/default/grub file but none of them worked. Whenever I tried this manipulation the screen still didn't change, however the bubble stopped functioning properly.

This is not a problem of the Fn shortcut. Even when I try to change it in the Brightness and Lock on System Settings, the bar does scroll but the screen remains unchanged.

Does any one has a way around this mystery?

Answer 1

This answer worked for me.

Open a terminal

Type sudo su root and press Enter

Type echo 400 > /sys/class/backlight/intel_backlight/brightness. Use the brightness level you wish.

Type exit

Close terminal

Answer 2

LCD Brightness Control

This is fixable by editing one's xorg.conf file. Open a terminal window and type the following:

sudo nano /etc/X11/xorg.conf

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

You will need to restart your graphical server (or reboot) for this change to take effect.

Answer 3

You may have a look at this thread:

http://ubuntuforums.org/showthread.php?t=2033273&page=2 (message 11, 12 and following).

Adding the scripts described in the above thread:

/etc/acpi/brightdown.sh

/etc/acpi/brightup.sh

/etc/acpi/events/sony-brightness-up

/etc/acpi/events/sony-brightness-do`wn

solves the problem and enables the Fn+F4 or Fn+F5 keys.

Answer 4

Install xbacklight (sudo apt-get install xbacklight) and try this command to reduce the brightness by 20%: xbacklight -20. If it works, then try this script (remember that you have to install inotify-tools and configure some of the paths inside the script -- there are comments inside for help):

How to use xbacklight with brightness keys in a VAIO

It worked on my VPC.