Ubuntu: Cannot change backlight brightness Ubuntu 14.04


This morning I found that I cannot change the brightness of my Dell XPs 13 laptop's display anymore. I tried the following to change the brightness

  • Use keyboard brightness keys
  • Run the commands shown below
  • Boot with kernel option acpi_backlight=vendor. This resulted in a dell_something folder being present in the /sys/class/backlight folder. Changing the brightness file in that folder does not help.
  • Add 'intel_backlight' to xorg.conf
  • Set "load legacy option ROM" BIOS option to enabled and "secure boot" to disabled
  • Boot with kernel option i915.disable-pch_pwm=0
  • Boot from a fresh Ubuntu 12.04 USB stick installation. I can still not control the brightness. This is strange as the laptop came preinstalled with 12.04. Maybe this a hardware problem?
  • Install latest intel video driver

Any ideas why this broke suddendly? I've upgraded from 12.04 to 14.04 in April and till yesterday the brightness keys were working fine.


echo 100 > /sys/class/backlight/intel_backlight/brightness  echo 100 > /sys/class/backlight/acpi_video0/brightness  


I got a fix for my dell 5521 laptop, working for Ubuntu 14.04 but will work for kernels v3.13+.

  1. Open /etc/default/grub

    sudo nano /etc/default/grub  
  2. to change the line

    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"  


    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video.use_native_backlight=1"  
  3. then save and exit and

  4. run

    sudo update-grub  
  5. then reboot

The explanation is that ACPI adds its own back light control even if one is already present which is intel_backlight, adding this line forces CPI to use the Intel back light.


For me, solution listed on bug report #1249219.

Basically it works creating the /usr/share/X11/xorg.conf.d/20-intel.conf file with the following lines:

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


I used this solution, it's very simple and easy:

  • Install xbacklight
  • Open Startup Applications
  • Add a new startup item, (give it a name and in the command line type: xbacklight -set 50)

50 gave me the level of brightness I needed but you may need to experiment with the values for your particular system.


I have read A LOT of articles

Here is what I did, as I've been struggling with this for a long time...

Creating and modifying /usr/share/X11/xorg.conf.d/20-intel.conf file with the following lines...

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

...didn't work at all

I was using xbacklight option for some time, but it didn't satisfy me, as I knew it must be possible with Linux native way.

I've tried many GRUB options without effect, so I was googling again and again, coming back to solve this issue.

Today I came to the solution, which is following:

  1. You need to kill your display manager, to create new Xorg.conf file (because it runs X server):
    • Press Ctrl+Alt+F1 (Dont panic, while your Window system is runing, you can go back with Ctrl+Alt+F7)
    • typesudo service lightdm stop and press Enter(e.g. gdm, kdm, xdm)
  2. Create new Xorg configuration file
    • type X -configure and press Enter
    • type mv xorg.conf.new /etc/X11/xorg.conf and press Enter
  3. Start X Server (you can do it all without GUI via command line, but I was more comfortable with this aproach):
    • typesudo service lightdm start and press Enter(e.g. gdm, kdm, xdm)
  4. Modify Xorg.conf file
    • navigate to /etc/X11/xorg.conf and open Xorg.conf (in my case latest was xorg.conf.05312015) via leafpad (e.g. gedit, pluma)
    • search for Section "Device" and then for Driver (on my PC it said Driver "intel" by default, but it could be something else, so change it to intel)
    • add line Option "Backlight" "intel_backlight" after Driver "intel" (it doesn't really matter where, as long as it stays in Device Section)
    • save
  5. Modify GRUB

    • sudo gedit /etc/default/grub (e.g. leafpad, pluma...)
    • set to GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=" (acpi_osi= did it for me, other options didn't work...)
    • in terminal type sudo update-grub and press Enter
    • or use GRUB customizer:

    sudo add-apt-repository ppa:danielrichter2007/grub-customizer sudo apt-get update sudo apt-get install grub-customizer

Grub customizer

  • press Save in upper left corner, which will update GRUB for you

    1. Restart and profit

Funny thing is, that code is exactly the same as in /usr/share/X11/xorg.conf.d/20-intel.conf, but that way it worked as expected!


I created a simply script:

touch /usr/bin/brightness  

The contents as follows:

#!/bin/bash  echo $1 | sudo tee /sys/class/backlight/intel_backlight/brightness  

This allows you to then run the following from the command line:

brightness 100  brightness 4000  

The values depend on your max brightness values which you can get by running:

cat /sys/class/backlight/intel_backlight/max_brightness   

Don't forget to make the script executable:

chmod +x /usr/bin/brightness  

I opted not to change the permissions of the brightness file and keep the sudo part for security reasons.


  1. Open Terminal, run gksudo gedit /etc/rc.local

  2. It will ask for password. Type your password.

  3. Then, the text editor will pop up with rc.local file opened. It contains some stuff and in the end exit 0.

  4. Before that exit 0 line, add below commands to reduce brightness in Ubuntu:

    echo x > /sys/class/backlight/intel_backlight/brightness  echo y | tee /sys/class/backlight/acpi_video?*/brightness # (optional) > /dev/null  

    where 0 ≤ x ≤ 4882 and 0 ≤ y ≤ 10.

  5. That's it. Save and restart your machine.


It works for ubuntu 14.04 for me. Minimum brightness setting:

echo 0 | sudo tee /sys/class/backlight/acpi_video0/brightness   


echo 7 | sudo tee /sys/class/backlight/acpi_video0/brightness  


This worked for Acer 5830TG in Ubuntu 16.04 LTS

  1. First make sure your system uses Intel Graphics card

    $ ls /sys/class/backlight  intel_backlight  

    At least intel_backlight should be mentioned

  2. Now download and install Intel graphics driver and follow instructions.

  3. On the grub configuration file /etc/default/grub modify the following line:

    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"  


    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"  
  4. Then update grub

    sudo update-grub  
  5. Create and open the file /usr/share/X11/xorg.conf.d/20-intel.conf:

    gksudo gedit /usr/share/X11/xorg.conf.d/20-intel.conf  
  6. Add the following text:

    Section "Device"          Driver      "intel"          Option      "Backlight"  "intel_backlight"          Identifier "card0"  EndSection  
  7. Save and reboot.


I had the same issue on my Samsung laptop with my Ubuntu 14.04 and kernel 3.19.

For me the solution was setting the line in the configuration file /etc/default/grub as following:

 GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video.use_native_backlight=0"  

and then updating settings:

sudo grub-update  

If t will not help you can try to turn off Legacy (CMS) boot option in BIOS.

Before I was trying:

  • Setting /usr/share/X11/xorg.conf.d/80-backlight.conf file
  • GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
  • GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video.use_native_backlight=1"


I had the same problem on my lenovo ideapad Z500.

I found this trick that worked on my ubuntu 16.4:

On the grub configuration file /etc/default/grub modify the following line:

    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"  

by adding this string: acpi_backlight=vendor. (In my case i removed acpi-osi=linux and replaced, so, in the end it was:

    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"  

Update grub by launching:

   sudo update-grub  

Then create a xorg configuration file like this:


and copy in it this text:

   Section "Device"          Identifier  "Intel Graphics"          Driver      "intel"          Option      "AccelMethod"     "sna"          Option      "Backlight"       "ideapad"           BusID       "PCI:0:2:0"      EndSection  

Save the file, Reboot.

Also you can try to use fn brightness keys outside of ubuntu (before it starts or in the bios settings). it could work. try it.


Xubuntu 16.04 (Samsung N150 - Intel GMA3150):

Fixed brightness control issue by creating /usr/share/X11/xorg.conf.d/20-intel.conf with the following text:

Section "Device"          Driver      "intel"          Option      "Backlight"  "intel_backlight"          Identifier "card0"  EndSection  

Thanks to: ArchLinux - Samsung_N150_Backlight and Daria


clone the following script and run it from a root terminal after pasting the script in /bin

git clone https://github.com/el-beth/backlight.sh.git


This worked for my eeepc seashell series:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux"  

This is from http://ubuntuforums.org/showthread.php?t=1412922, and they got it from http://wiki.debian.org/DebianEeePC/Model/1005pe.


I found solution after years of searching and it's works very well.

Just added in /etc/default/grub GRUB_CMDLINE_LINUX_DEFAULT string acpi_backlight=video.

Lenovo Ideapad Z500: Intel HD4000, GeForce 740m


Here is what I did:

$sudo su -  #more /sys/class/backlight/intel_backlight/brightness   19200  

I changed the value to 50200

#nano /sys/class/backlight/intel_backlight/brightness  50200  

and saved it. It changed the brightness immediately. I am using An Asus X441N laptop: https://www.asus.com/Laptops/ASUS-VivoBook-Max-X441NA/

Note:If u also have question or solution just comment us below or mail us on toontricks1994@gmail.com
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