Re: [PATCH 2.6.18-mm2] acpi: add backlight support to the sony_acpi driver

Matthew Garrett
2006-10-11T07:04:20Z

On Wed, Oct 11, 2006 at 08:59:04AM +0200, Arjan van de Ven wrote:

> it'd also be nice if the linux-ready firmware developer kit had a test
> for this, so that we can offer 1) a way to test this to the bios guys
> and 2) encourage adding/note the lack easily

Sure. Reading /proc/acpi/video/*/*/info should tell you whether a device
is an LCD or not. The brightness file should then contain a list of
available brightnesses, and writing one into there should change the
screen value. There's a patch somewhere that ports this to the
/sys/class/backlight infrastructure, but I don't think it's applied yet.

I'd write a test up for you, but I don't actually seem to have any
hardware that implements this properly. Tch.
--
Matthew Garrett | mjg59@srcf.ucam.org