LCD backlight turns off when between discrete levels, both from hotkeys and from dim-on-idle.
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
gnome-power-manager (Ubuntu) |
Invalid
|
Undecided
|
Unassigned | ||
linux (Ubuntu) |
Fix Released
|
Medium
|
Unassigned | ||
linux-source-2.6.22 (Ubuntu) |
Won't Fix
|
Low
|
Unassigned |
Bug Description
Binary package hint: gnome-power-manager
When gnome-power-manager dims the screen when on battery or when idle, the backlight turns entirely off.
In addition, during the fade the screen blinks: 100%, OFF, 75%, OFF, 50%, OFF.
cat /proc/acpi/
levels: 100 37 12 25 37 50 62 75 87 100
current: 100
The screen is turning off whenever something requests a brightness level between the available discrete levels; thus the default dim-when-inactive brightness of 30 turns the backlight off. For a while, I thought my system was freezing at a black screen at login (battery) or idle (AC), until I remembered the brightness controls.
One factor in this is the new /sys/class/
This structure does not seem to provide the same, necessary information, such as available discrete brightness levels.
/sys/
/sys/
/sys/
HAL lists num_levels=101, while ideally it should be 8 or 9. Better yet, the kernel itself should provide the discrete levels, or rounding issues may appear.
Oddly. the brightness levels 12, 37, 62, and 75 work through echoing into /proc, but turn the backlight off if used in /sys, and thus HAL or g-p-m.
Echoing invalid values into /sys turns the backlight off, but echoing into the /proc structure returns 'invalid argument'.
Note: the data under /sys/class/
(My DSDT also provides sys/class/
Edit: As of the beginning of October 2003, changes to the kernel 'video' modue and HAL make me now have to hit my brightness keys 5 times before reaching the next brightness level; before, the brightness keys were still managed by the kernel.
In addition, upgrading HAL breaks brightness changes until the next boot.
description: | updated |
description: | updated |
I can confirm, when using the laptops brightness control buttons, a small window pops up showing brightness level (great), but it blinks while I change the brightness, which is very irritating.