# What manages the backlight?

## denysonique

I have a Samsung R510 laptop and as of writing this post the back-light cannot be controlled by the kernel.

The only one way do change the brightness of the backlight is via a direct pci call using setpci. For example:  setpci -s 00:02.0 F4.B=BB. 

How do desktop environments such as KDE and GNOME control the back-light?

I need this information because I would like to write an ebuild samsung-backlight that fixes this problem and modifies the programs called by GNOME and KDE that control the back-light.

Gentoo needs to be the first distro that supports laptops from the series of my laptop to have a working back-light!

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## paulusbrand

I use the brightness applet with gnome. You can add it to your panel if you merge gnome-applets.

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## chithanh

The standard backlight controls are in /sys/class/backlight and are usually provided by the acpi video and backlight class device drivers.

EDIT: A google search reveals that the backlight should be supported by the samsung_laptop driver in the staging section.

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## denysonique

I think GNOME and KDE don't manipulate /sys/class/backlight directly. Maybe they call something that then manipulates /sys/class/backlight interface. The samsung_laptop driver unfrotunately does not work for my model of my laptop.

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