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.

Answer 5

More than 2 years back i had similar problem with my dell inspiron laptop.At that time

This work by kamal mostafa solved my problem and this patch has been already applied to 3.1 kernels

Now i have upgraded to sony vaio ultrabook and i have similar problem.After some research and hacking i am able to solve brightness control to normal.

1. First i found acer_wmi and sony_laptop kernel modules are loading while startup using lsmod command.
2. Second i found was two backlight on /sys/class/backlight acpi_video and intel_backlight . *here brightness keys working smoothly with /sys/class/backlight/acpi_video/brightness but changes are not reflected on screen* *second screen brightness changes do get reflected with intel_backlight * echo 400 > /sys/class/backlight/intel_backlight/brightness

3. acer_wmi and sony_laptop both modules checks if acpi_video is compatible and loads the module. *here i blacklisted acer_wmi and added kernel boot parameter to disable acpi_video and sony backlight which gets loaded by sony_laptop module while it detects acpi_video is incompatible*

   GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor sony_laptop.backlight=0"

Now there will be only one intel_backlight in /sys/class/backlight folder which easily gets bind with gnome-powe-manager functioning brightness control keys.i am sure at this point it will also work kde's power-management tool

During boot you will find message but it works fine:

[ 9.999247] sony_laptop: 0' invalid for parameterbacklight'

Answer 6

This worked on my Sony Vaio T13:

1. open your terminal (Ctrl+Alt+t)and type
   sudo acpi_listen.

Now this terminal will "listen" to the keyboard.

2. Hit the shortcut for brightness down and brightness up, in this case: Fn+F4 and Fn+F5. You should see how this is interpreted on terminal. Typically something like:

sony/hotkey SNC 00000001 00000011
sony/hotkey SNC 00000001 00000010

or similar.

3. Open another terminal without closing the previous one. And type:
   gksu gedit /etc/acpi/events/sony-brightness-up

this will open a text file. Copy and paste in the text file this code:

event=sony/hotkey SNC 00000001 00000011
action=/etc/acpi/brightup.sh

make sure your doing it right (that's why you should have kept the first terminal open): if the output from step 2 was different then you'd have to type

event="whatever-was-in-your-output"
action=/etc/acpi/brightup.sh

save and close the text file.

4. In terminal type: gksu gedit /etc/acpi/events/sony-brightness-down
   this opens a different text file. In the text file copy-paste this (again, change the bit "event= ..." if necessary):

event=sony/hotkey SNC 00000001 00000010
action=/etc/acpi/brightdown.sh

save and close.

5. In terminal type gksu gedit /etc/acpi/brightdown.sh
   and in the text file that will open type:

#!/bin/bash
curr=cat /sys/class/backlight/intel_backlight/actual_brightness
if [ $curr -gt 406 ]; then
curr=$((curr-406));
echo $curr > /sys/class/backlight/intel_backlight/brightness;
fi

save and close.

6. In terminal type:gksu gedit /etc/acpi/brightup.sh
   and in the document type:

#!/bin/bash curr=cat /sys/class/backlight/intel_backlight/actual_brightness
if [ $curr -lt 4477 ]; then
curr=$((curr+406));
echo $curr > /sys/class/backlight/intel_backlight/brightness;
fi

save and close.

To make these scripts executable, type in terminal:
sudo chmod +x /etc/acpi/events/sony-brightness-up
sudo chmod +x /etc/acpi/events/sony-brightness-down
sudo chmod +x /etc/acpi/brightdown.sh
sudo chmod +x /etc/acpi/brightup.sh

7. Finally, restart acpid by typing in terminal:
   sudo service acpid restart