Xubuntu 10.10 brightness control

[justanotherguy]

Hello.

I changed Ubuntu 10.04 to Xubuntu. Most features provided by the drivers and samsung-tools work fine, except for not very important ones. And there is this problem with backlight control. Should I press Fn+Brightenss Up (or Down), the backlight automatically rises up to the maximun (or falls to the minimun). I think the problem isn't whitin the backlight driver itself, but rather in keyboard. Still, i have no clue where to start looking. Any ideas?

[justanotherguy]

It appears that problem is with ACPI. dmesg says

Code: Select all

[  521.070694] ACPI: Failed to switch the brightness

cat /proc/acpi/video/IGD0/DD0*/brightness

Code: Select all

<not supported>
<not supported>
<not supported>
levels:  7 15 24 30 45 60 80 100
current: 100
<not supported>

Booting system with acpi=off enables backlight to operate properly, but this parameter disables some really important features.

I don't understand why this stuff refuses to work. Can somebody explain it to me?