Comment 18 for bug 415023

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Genowefa Pigwa (gefa-poczta) wrote :

I finally understand what is going on.

The kernel stuffs the keystrokes into the keyboard controller to change the brightness. I have not found this in the kernel source, but putting various numbers to /sys/devices/virtual/backlight/acpi_video0/brightness changes the brightness and makes the halevt -i report the keystrokes.
The gnome-power-manager receives these keystrokes and tries to change the brightness, and as the levels round incorrectly, we have an infinite loop.
There are two possible solutions then:
 - make the gnome-power-manager not attempt to change the brightness on receiving the keystrokes
 - use xrandr --output LVDS --set BACKLIGHT_CONTROL combination
   I have put this line in /etc/X11/Xsession.d/99setbacklittocombination. It works for me. I do not use KMS, for KMS you should put LVDS1 instead of LVDS