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My laptop has intel hd graphics 4400, and it doesn't work well on ubuntu 14.04 , so I upgraded to ubuntu 15.04.

It works fine, but i cannot change my brightness.

The funny thing is that i can change the brightness by terminal command or at the system setting.

The max brightness value is 937, so i can edit the brightness to 300, 500 or other values by terminal command. Also I can change it brighter by function key.

But I cannot make it darker by function key!

Does anybody know how to fix this?

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1 Answer 1

Reset to default
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Try this:

  1. Open a terminal

  2. Run pkexec gedit /etc/default/grub

  3. Type your password and the text editor will open. Find the line containing GRUB_CMDLINE_LINUX=""

  4. Change it to GRUB_CMDLINE_LINUX="acpi_backlight=vendor".

  5. Save the file and close the text editor.

  6. In the terminal, now type sudo update-grub.

  7. Reboot, and see if it works.

Source: Brightness function keys not working and Ubuntu 12.04 Wifi/Brightness Fn Keys don't work and http://thehtd.blogspot.co.uk/2012/08/brightness-problem-in-ubuntu-1204.html

By the way, it would be helpful if you could specify what laptop you're using.

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  • This is not needed if brightness can be controlled.
    – Pilot6
    May 26, 2015 at 14:17
  • @Pilot6 what do you mean?
    – David Bailey
    May 26, 2015 at 14:18
  • I mean that editing grub config is not needed in this case.
    – Pilot6
    May 26, 2015 at 14:19
  • I've seen this answer in multiple locations, and it seemed to work for most people. Have you tried it?
    – David Bailey
    May 26, 2015 at 14:20
  • Yes, this answer works in many cases, but this is not that case.
    – Pilot6
    May 26, 2015 at 14:23

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