The nature is getting greener everyday, so why can’t we? I decided to invest a bit of my time solving a problem with Dell laptops running Ubuntu and the LCD brightness. The root of this problem is detailed in the Dell Latitude D600 laptop page on the Ubuntu Wiki. To shortly summarise the current release (7.04) of Ubuntu does not manage to talk with the Dell hardware properly to get the brightness state and to modify it. Therefore, Ubuntu cannot dim the LCD brightness to save energy on such laptop.
This post briefly offers some technical background before pointing to a guide in wikishelf, which will explain how to activate the control of the LCD brightness and take advantage of the Gnome Power Manager facilities to save some more battery life.
For other tips and tricks to lower your power consumption on Linux in general, try this article about Linux power management, how to optimise power consumption, most of these information are not specific to Dell laptops or Ubuntu, they can even be applied on desktop computers to save energy.
Small technical background
The software layer that abstracts the hardware from the user application is called HAL (Hardware Abstraction Layer). The version released with Ubuntu 7.04 was not able to talk with the LCD brightness hardware implementation of most Dell laptops. Recently this changed, a newer version of HAL has been back-ported to the current stable release of Ubuntu. In Debian terminology, a back-port is a software that is currently validated in a newer distribution release (for example the unstable or development release) and is made available for some earlier distribution releases.
How to activate the LCD brightness control
So, the newer HAL version is able to support Dell LCD backlight control, however it is not built in – as of today – in the current published package. Therefore, updating Ubuntu 7.04 to the latest HAL in the back-port repository will have no effect. It is a bit more tricky to perform and requires some manipulation. This is why I wrote a small guide which explains how to activate the HAL Dell LCD backlight feature.
This guide introduce some concept to save more battery power by using the newly activated feature.
This article is intended to users familiar with Linux (although I have tried to make it as simple as possible), daring user not familiar with Linux should be able to understand it too
I intend to write in the near future another post with binary packages (so a much easier installation), which I will made available. So come back in a couple of days.