xbacklight and Knoppix 7.7.1

[philo]

ON the same computer, xbacklight was working well with Knoppix 7.4 and 7.6.

It is not working for Knoppix 7.7.1. The command:


xbacklight -get

returns:


No outputs have backlight property

[philo]

As a followup, using the function keys for brightness (in my case: fn+Alt+F5 or F6) seems to be remembered. So, at least for me, there is a workaround.

[philo]

The "No outputs have backlight property" error is apparently because xbacklight does not choose the right directory in /sys/class/backlight. Running:


ls /sys/class/backlight

shows that directory is named intel_backlight.

We should then be able to specify the directory by setting the Backlight option of the device in xorg.conf, configuring the section "Device" as follows:


/etc/X11/xorg.conf

Section "Device"
Identifier "Card0"
Driver "intel"
Option "Backlight" "intel_backlight"
EndSection

[philo]

Actually only these 2 lines need to be inserted:



Driver "intel"
Option "Backlight" "intel_backlight"

Should also have mentioned the link for the solution to that issue:

https://wiki.archlinux.org/index.php/Backlight#xbacklight