Four steps of brightness changing after pressing a brightness key only once
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
gnome-power-manager (Ubuntu) |
Invalid
|
Undecided
|
Unassigned | ||
hal (Ubuntu) |
Invalid
|
Undecided
|
Unassigned |
Bug Description
Binary package hint: gnome-power-manager
As recommended by Andreas Wenning in Bug #207473, I'm opening a new bug report. Although there's several similar bugs already reported, I didn't find one I could really consider a duplicate.
My laptop is Dell Vostro 1400 with a GeForce 8400M GS and I'm using Hardy. When I press one of the brightness controls keys (Fn + Up or Fn + Down), four steps of brightness changing happen instead of just one. There seems to be a consensus in Bug #207473 that the problem lies on both hal and the desktop manager software responsible for power management. They both try to adjust the brightness and they both do two steps instead of one. A fix for kde-guidance, which supposedbly reduces the number of steps to two (in other words, fixes the problem on kde side but not on the hal side, which is still being worked on) is already available in hardy-proposed.
An example of what lshal -m reports when I press Fn + Up only once:
06:53:28.008: computer_
06:53:28.010: computer_
06:53:28.011: platform_
06:53:28.200: platform_
Some other observations:
1) Executing /etc/acpi/ video_brightnes sdown.sh or /etc/acpi/ video_brightnes sup.sh changes the brightness just one step, but tweaking those scripts, or even deleting them, has no effect in the bug. It seems they are not called at all when the Fn keys are pressed, I don't know if this is expected behavior.
2) Blacklisting the video module fixes the four-step behavior, but causes other problems. A brightness change pop-up does not appear anymore, the brightness applet loses sync with the current brightness and trying to change brightness through the applet causes a two-second hanging for each step.
3) hal and gnome-power manager also seem to be conflicting in automatic brightness adjustment. A quick flicker when I unplug the ac cable indicates that the brightness was adjusted twice.