Re: brightness control on thinkpad t61p

[Henrique de Moraes Holschuh <hmh@hmh.eng.br>]

On Tue, 08 Jan 2008, Richard Purdie wrote:
> On Tue, 2008-01-08 at 15:54 +0000, Matthew Garrett wrote:
> > On Tue, Jan 08, 2008 at 03:45:02PM +0000, Richard Purdie wrote:
> > 
> > > I did't get enough context above but I went through the archives and it
> > > seems this is about linearising backlight values.
> > 
> > Indeed. The ACPI spec provides a range of 0-100, without specifying what 
> > this actually means (it gives brightness and power consumption as two 
> > different examples). Implementations are only required to support a 
> > subset of these, with the others being ignored. The current hook into 
> > the backlight class exports this range but provides no means for an 
> > application to determine which values are valid - I'd prefer to just 
> > flatten the range to remove the holes. Given the lack of standardisation 
> > in the real meaning of the values, I don't think exporting the 0-100 
> > range buys us anything.
> 
> I agree with that. 0-100 actually breaks a useful and valid way the
> class gets used in the "brightness + 1" case...

So be it, then.  But my request that we get a way to add the information we
are losing to the backlight class still stands.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh