Screen brightness not working

Solution 1:

To get working brightness keys, try the following.

Run the command:

sudo -H gedit /etc/default/grub

Change this line

GRUB_CMLINE_LINUX_DEFAULT="quiet splash"

to something like below

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor

Execute sudo update-grub and reboot. See if brightness keys are working.

It is still possible Ubuntu won't remember your brightness settings. So you have to change brightness each time.

Please let us know the result as many Sony users are facing this problem.

This is for setting brightness manually after doing the above steps.

Try following for paths shown by ls /sys/class/backlight/*/brightness and replace accordingly.

For example, paths will be like:

/sys/class/backlight/acpi_video0/brightness

For the above path Get the maximum brightness:

cat /sys/class/backlight/acpi_video0/max_brightness

Try a lower value to set the brightness, say output is 16 so I will try with half of it:

echo 8 | sudo tee  /sys/class/backlight/acpi_video0/brightness

If this works, make this happen in each login automatically by doing the following

sudo -H gedit /etc/rc.local

Enter this line just before exit 0. It should look like:

echo YOUR_VALUE_HERE > /sys/class/backlight/acpi_video0/brightness
exit 0

Also you can try with xdotool Install xdotool

Solution 2:

For those who end up here while looking for a solution, I've found the text below from here and this works for my Ubuntu 12.04 64bit.

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.

Solution 3:

Actually both grub and xorg.conf modifications are needed.

First modify /etc/defaults/grub to add ACPI parameters. The GRUB_CMDLINE_LINUX_DEFAULT line may then look liee:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor"

Update GRUB to apply that change, by running the command:

sudo update-grub

Second, in the file /etc/X11/xorg.conf, find the in Device section and add Option EnableBrightnessControl, so it looks like this:

Section "Device"
     Identifier     "Device0"
     Driver         "nvidia" 
     VendorName     "NVIDIA Corporation" 
     BoardName      "GeForce GT 330M" 
     Option         "RegistryDwords" "EnableBrightnessControl=1"
EndSection

This works for me on Samsung R780 with Nvidia GeForce 330M.

Solution 4:

I had the same problem with my Vaio and Ubuntu.

I got it working with the nvidiabl-module and the oBacklight script.

The script is available from this repository, and these instructions may be helpful.

Or use the newer DKMS-based way described in the README file. If you use that technique, you really should read that file thoroughly. However, one method that should work is to download a .deb file and install it. The project is inactive so nvidiabl-dkms_0.87_all.deb will likely remain the latest .debpackage. You can download and install that package with these two commands:

wget https://raw.githubusercontent.com/guillaumezin/nvidiabl/master/install/deb/nvidiabl-dkms_0.87_all.deb
sudo dpkg -i nvidiabl-dkms_0.87_all.deb

The README has information on other ways to install, as well as uninstalling.

Solution 5:

Install xbacklight:

sudo apt-get install xbacklight

You can set brightness to X% as (no sudo required):

xbacklight -set X

To make the setting permanent, go to Startup Applications and add a new startup program, with the following command (where X% is your desired brightness):

xbacklight -set X

Modifying /etc/rc.local as many others have suggested does not work for me (on a Dell Studio 1535).