[acpi-jp 3093] Re: Update on ACPI with FreeBSD CURRENT on ThinkPad T30

[Nate Lawson]

On Tue, 2 Mar 2004, Grover, Andrew wrote:
> > From: owner-acpi-jp at jp.FreeBSD.org
> > [mailto:owner-acpi-jp at jp.FreeBSD.org] On Behalf Of Randy Bush
> > > Try using the sysctls from the new acpi_video module to turn off the
> > > backlight, perhaps by turning the brightness way down.
> >
> > i am on a t40p and have tried a lot of this to no avail.
>
> My understanding is that actually turning off the backlight is not done
> via _BCM. But, I still don't know exactly how it *is* done. _PS3 might
> do it, but some people have hinted that this is something that the video
> driver is supposed to know how to do.

I believe you're correct.  On others, the _PSx methods do control
backlight.  However, for this platform most is done through SMI so I'm not
sure.

-Nate