Ubuntu
linux package

  1. Bug #284319
  2. Comment #8

Comment 8 for bug 284319

Revision history for this message
Dirk (rptq) wrote : Re: mute, brightness buttons on new HP 6930p laptop

The value in /sys/devices/virtual/backlight/acpi_video0/brightness also changes whenever one of the three events mentioned above happens.

Today I found the following: When I set
xrandr --output LVDS --set BACKLIGHT_CONTROL native
then I can control the brightness using the function keys, xbacklight and xrandr. The gnome applet also works, but is too slow to be useful. In this mode the values in /sys and /proc/acpi don't change anymore. Dis/Connecting the A/C power has no impact in this mode.

However, there is still a dependency on the power status during boot. It seems that the maximum brightness available is still set at that time. I have not found a way to increase the brightness beyond that level except plug-in & reboot.

xrandr --output LVDS --set BACKLIGHT_CONTROL kernel
switches everything back to as it was before.