Can't adjust screen brightness on Ubuntu 12.04LTS

Question

My laptop is Samsung NP-Q430-JS03US. I have searched for the solution. I have tried editing grub acpi_osi=Linux and acpi_backlight=vendor, but still didn't work.

Please help.

Answer 1

Try using xbacklight.

• Install it by running sudo apt-get install xbacklight in a terminal.
• Change brightness by xbacklight -set <level>, where <level> is an integer ranging from 0 to 100 (lowest brightness to highest).

For example, to set medium brightness one would use

xbacklight -set 50

Answer 2

Your laptop is Optimus-enabled. That means that it has two video cards: an Intel card and a Nvidia one (meant to be used for games only). This is problematic because Optimus has been designed to work with Microsoft Windows, and Ubuntu won't play very good with it.

Please check your BIOS setup, whether the Optimus option is enabled or not --if there's even any Optimus settings.

With Optimus enabled, your display will be managed by the Intel card. The brightness controls should work out-of-the-box. The Nvidia card will be fully-powered all the time though, and you need to setup Bumblebee to avoid this and to be able to use the Nvidia card for gaming.

With Optimus disabled, your display will be managed by the Nvidia card, and you'll lose the brightness controls, since the Nvidia card is not capable of accessing them.

Answer 3

I believe you should sudo open /etc/default/grub, find the line that starts with GRUB_CMDLINE_LINUX_DEFAULT and make it look like this:

GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash pcie_aspm=force acpi_osi=Linux i915.i915_enable_rc6=1″

Answer 4

I have a Samsung NP300E5a with Optimus. Same problem after upgrading to Kernel 3.5.0-31-generic. I found a solution that works for me here "Brightness problem on a Samsung 530U3B". Details below

Add the "Linux On My Samsung" repository to the sources list: Code: sudo add-apt-repository ppa:voria/ppa Update the programs list: Code: sudo apt-get update Install samsung-backlight: Code: sudo apt-get install samsung-backlight Restart the system and check if backlight control works