Ubuntu
linux-source-2.6.22 package

  1. Bug #173652
  2. Comment #114

Comment 114 for bug 173652

Revision history for this message
kaervos (eudoxus) wrote : Re: Unable to adjust screen brightness on recent Sony Vaio notebooks, Intel GMA adapter

Vaio VGN FS840/W (915GM chipset) here, using the latest xserver-xorg-video-intel v2:2.4.1-1ubuntu10. I also have this problem with my backlight. After quite some time debugging the gnome brightness applet and gnome-power-manager, I realized gnome-power-manager is seemingly dependent upon xrandr. When running gnome-power-manager with --no-daemon and --verbose, I can see that it thinks the range for my brightness is (0,0). Xrandr also thinks the range is (0,0). If I change BACKLIGHT_CONTROL to legacy with xrandr, --prop will say my backlight range is (0,255), which is reflected in gnome-power-manager. Unfortunately, adjusting the BACKLIGHT with xrandr or the brightness applet does nothing (I have tried setting BACKLIGHT_CONTROL to native, kernel, legacy and combination with no results).

When I run xbacklight, it returns "nan".

If I write a value from 0 to 7 into /class/backlight/sony/brightness, my screen brightness will be adjusted. I understand this to be a function of the sony-laptop module however, not the video driver. The brightness applet doesn't use this method, so it is effectively broken.

If I use the VESA driver, xrandr and the brightness applet work as expected.

I assume this has to do with the intel video driver?