[Intel-gfx] Legacy backlight control with KMS and BACKLIGHT property

[Greg KH]

On Fri, Aug 14, 2009 at 10:16:06PM -0700, Jesse Barnes wrote:
> On Fri, 14 Aug 2009 12:28:47 -0700
> Greg KH <greg at kroah.com> wrote:
> 
> > On Fri, Aug 14, 2009 at 12:08:21PM -0700, Greg KH wrote:
> > > Here's a first cut at such a driver.  It works for me on this
> > > laptop, but note that it will try to work on _any_ Intel-based
> > > system.  I'll figure out how to do this only for specific machines
> > > based on DMI data next.
> > 
> > And here's one that is set for DMI data to only load on the proper
> > ones.
> > 
> > I'll push this upstream now, if there are no objections.
> 
> Yeah, looks fairly reasonable.  This code should work on most pre-965
> chipsets too, since they share the LBB regs.  There are a couple of
> other things to take into consideration: I think the VBIOS indicates
> whether the controls are inverted (i.e. a value of 0xff is minimum
> brightness) and there may also be some stepping info.

Where can I find the register information so that I can properly read
this kind of thing?

> So ultimately I'd like to see this be part of the i915 driver as one of
> a few different methods supported (hopefully we can autodetect them
> better than the 2D driver though, using the VBIOS and DMI in the
> kernel).

That would be nice, I have no objection for that happening eventually.
Feel free to take the driver and merge it into yours if you feel that is
better.

thanks,

greg k-h