August 28, 2009

Can't change brightness on Acer 4810t (8.04)



8.04 all working nice and stable on my new Acer 4810t dual core, but still with some outstanding issues.

I haven't found a way to get the brightness to change at all, am wondering if anyone can help.

Looking around the brightness control could be here:


and if I try

cat /proc/acpi/video/VGA/LCD/brightness

I get something like

~$ cat /proc/acpi/video/VGA/LCD/brightness
levels: 100 80 30 40 50 60 70 80 90 100
current: 70

which I've just noticed is controlled by the hotkeys. Unfortunately it has no effect on the brightness. Using the echo command has no effect on it.

There is also


and if I try

cat /sys/class/backlight/acer_acpi/brightness

I get


but echo changes nothing.

There is also


and if I try

cat /proc/acpi/acer/brightness

I get


but the echo command makes no difference.

Any ideas where I'm going wrong?