No backlight variation on Acer laptop

[eden6000]

Hi everybody,
Acer Aspire 5310, intel gma950, puppies 4.31,kernel 2.6.30.5 (wow, how synthetic I am )....problem as subject, there is no way to change backlight intensity...with old 2.6.25 kernel it used to work, now dmesg reports "ACPI: failed to switch brightness, must be controlled by generic driver" (maybe the words are not correct, as I'm not on that laptop at the moment, but that's the sense...).
Any idea?

[itzme]

eden6000,

I have the same problem with 4.31 NOP, but form time to time it does actually work, I find that Fn+F6 works turning the light off and on ok, though I do have a problem with booting with low intensity even in the bios, googling came up with this as a fault with the lcd backlight inverter, if that is the case their around $40-$50 mark for a replacement unit.

[eden6000]

Hi itzme, I don't think it's a hardware problem, ubuntu on the same machine is able to change brightness level....
As for your problem, sometimes I've happened to boot and the screen was totally dark, in that case I had to turn the laptop off removing also the battery, then it worked again.

[jairomacon]

I think the kext is responsible for this.. as long as the kext is not loaded to the brightness It can be changed using the function keys.In intel gma950 ,you know that the function keys change the value of the register but somehow it gets ignored.. this is my best guess that the gma950 driver overrides the value or it has a trap on register and manually changes it back to max. try to change the kext.

[eden6000]

Thanks for your reply jairomacon...at the moment I have removed puppy from that laptop (I still have it on the desktop, btw ), so I cannot try what you suggest...anyway, what is kext??