x220 notes

[Hannes Mehnert]

Ciao,

On 03/14/2012 00:38, matt wrote:
> I have brightness control through raw acpi..."\_BCL" and friends seem to
> do nothing.
> 
> Most of the video methods differentiate between \VIGD (which seems to be
> a check for integrated graphics vs optimus, but that's still a guess)
> If \VIGD is true, brightness commands are sent to the EC, where they
> don't seem to do much yet. This is probably where we could enable
> something via EC/ibm-acpi?
> If \VIGD is false, brightness commands are handled in ACPI, although
> coarsely, via \VBRC.
> 
> \VBRC seems to allow control over the backlight, at least, so those of
> you with sore eyes or the 3-cell battery may have some success using the
> acpi_call port (Danger!)
> kldload acpi_call
> acpi_call -p '\VBRC' -i n (where n is 0-10)

Great news! Works for me. n is actually 0-16 (plus any other value which
turns the backlight off (-1 or 17 eg).


Thanks,

Hannes