vaio

Still working on getting my new laptop working exactly as I want it.

Today I wanted to use it in a low-light environment. Knowing that the hotkeys work (I've used the volume ones with much joy after my last laptop not having worked properly), I happily press the hotkey to lower the brightness. I watch the little OSD image with its lowering level, but no change to the brightness of my screen.

A little googling around points me in the direction of a kernel module called sonypi. I look for it on my local disk, and there's nothing. I look for it in apt-file, and it returns all the kernel sources. A bit more googling, and I find out that sonypi is now long gone (it was replaced by a module called sony-laptop)

A bit more hunting around my filesystem, and I have indeed got a module called sony-laptop. I make sure it is loaded, and try the brightness keys again. Still no luck.

The sys filesystem is used for such things as status of brightness, and there is a file called /sys/class/backlight/acpi_video0/brightness which takes values from 1 to 15. I manually set it to 1, and still no luck.

I finally found an answer, which was that it was the nVidia driver that was stopping it from dimming, nothing to do with the ACPI. I needed an extra option in my xorg.conf


Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
Option "RegistryDwords" "EnableBrightnessControl=1"
EndSection


Put that line in, restarted gdm3, and I'm sorted, I can now change the brightness using the function keys :)