Comment 48 for bug 446717

Well +1 :-(

I'm running Lucid on a 4810TG (with ATI, but not using the ATI card, because it drains my battery, see http://ubuntuforums.org/showpost.php?p=7933876&postcount=11 for a module that powers off the ATI card.)

My tries to fix include the following:
- Tried kernel 2.6.34 (package from http://kernel.ubuntu.com/~kernel-ppa/mainline/): No change, still get a freeze
- Tried the "acpi_backlight=vendor" boot option: No change
- Tried the "nomodeset" and "acpi_backlight=vendor" boot options: Seems to fix it, BUT nomodeset breaks lots of stuff for me, so this is not an acceptable option.

There is a working way to set the brightness (see script below Brightness Control > 9.10 on https://help.ubuntu.com/community/AspireTimeline/Fixes).

So all I need for a satisfactory workaround is a way to prevent the kernel and friends from trying to set the brightness. Didn't manage to do so yet:
1) Tried the "acpi.brightness_switch_enabled=0" boot option: No change (even seems like this does not work at all, because "less /sys/module/video/parameters/brightness_switch_enabled" still shows "Y")
2) Tried "echo 0 > /sys/module/video/parameters/brightness_switch_enabled" (as root): No change, still changes the brightness and freezes
3) Tried the "acpi_backlight=vendor" boot option and additionally "modprobe -r acer_wmi" (acer_wmi is the module I suspect to be in charge when the vendor option is passed): No change
4) 3) + "modprobe -r acer_wmi": No change

So: Is there some way to prevent the kernel and modules from trying to set the brightness? This is really annoying because when you remove the AC plug it tries to change the brightness and freezes...