brightness control on Dell Studio 1558

[Martín Jamilis <jamilismartin@gmail.com>]

Hello pals,

                I am having problems in adjusting the screen brightness on Dell Studio 1558 laptop with Debian Squeeze and intel graphics. Pressing the corresponding Fn keys doesn't change the brightness and gives the following error:

$ dmesg

...

[ 833.240055] ACPI: Failed to switch the brightness
[ 833.616022] ACPI: Failed to switch the brightness
[ 2182.884115] ACPI: Failed to switch the brightness
[ 2183.107576] ACPI: Failed to switch the brightness

I've tried  "echo 10 > /sys/devices/virtual/backlight/dell_backlight/brightness" without result. The same with other values. 

The file  /proc/acpi/video/GFX0/DD01/brightness    contains the line   "<not supported>".

There is a bug reported for Ubuntu in:        https://bugs.launchpad.net/ubuntu/+source/linux/+bug/568611 

There is a patch offered there but I couldn't make it work on latest stable kernel from kernel.org and there are no instructions available. 

Any ideas? 

Thanks in advance

Martín