[Intel-gfx] [PATCH] i915: Add native backlight support

[Zhenyu Wang]

On 2010.02.22 22:46:35 +0000, Matthew Garrett wrote:
> On Tue, Feb 23, 2010 at 08:40:35AM +1000, Dave Airlie wrote:
> > On Tue, Feb 23, 2010 at 3:05 AM, Matthew Garrett <mjg at redhat.com> wrote:
> > > Some machines do not provide a firmware or platform interface to backlight
> > > control, and so it's necessary to drive the hardware directly. Add support
> > > for a backlight driver to the drm. This will be flagged with the raw
> > > backlight type, allowing userspace to determine whether there is a more
> > > favourable backlight device available.
> > >
> > 
> > So there is one backlight, and a few different methods exposed to userspace
> > to use it? does the kernel not know which one it should expose? how does
> > userspace know any better?
> 
> Modules may be loaded at any time. The kernel could have some sort of 
> arbitration mechanism, but there's probably going to be some level of 
> heuristics involved - we could potentially do that in future, but it's a 
> moderate amount of extra complexity for no especially strong gain. 
> Userspace ought to be able to work things out based on the backlight 
> type attribute.
> 

Maybe this is a good fallback way, but looks you remove some PWM handling stuff
for like Pinview and Ironlake, and asle->cblv is not updated too. I suppose that
will break things, of coz no test yet.

-- 
Open Source Technology Center, Intel ltd.

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