I have Apple iMac 11,3 (27" LED, purchased in 2011) with a Radeon HD 5750 graphics card. When I installed Ubuntu 12.04 LTS, everything works fine except brightness control. I want to mention that I didn't install any additional driver.

I tried sudo update-grub after changing /etc/default/grub by acpi_backlight=vendor with/without acpi_osi=Linux. Nothing changes.

What can I do to fix this issue? Help is appreciated.

  • Excuse me, purchased in 2011 – carkaci Feb 3 '13 at 20:41
  • Please edit your question to provide additional information, don't put it into a comment. – guntbert Feb 3 '13 at 21:17

1) Download Grub Customizer, first by adding the repository:

sudo add-apt-repository ppa:danielrichter2007/grub-customizer

Then update the repositories and install the package grub-customizer,

sudo apt-get update && sudo apt-get install grub-customizer

2) In the General settings tab, add acpi_backlight=vendor and hit save.

3) Reboot and enjoy brightness control!

NOTE: I've only tested this on the latest release (13.04), can't guarantee this works on any other version.

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