[PATCH] [ACPI] Default to using the native backlight control on Windows 8 systems

[Jani Nikula]

On Fri, 11 Apr 2014, Aaron Lu <aaron.lu at intel.com> wrote:
> On 04/11/2014 04:13 AM, Matthew Garrett wrote:
>> The list of machines in the "Use native backlight" table is getting longer
>> and longer, which is a solid indication that we're doing something wrong.
>> Disable the ACPI backlight interface if the system claims to be Windows 8
>> or later.
>
> And has a native backlight control interface.

This. One thing we were doing wrong in i915 was unconditionally
registering a native backlight interface even when it was not
functional. We can't really know whether that is the case except by
trusting the VBT, and although we've been let down in the past, trusting
the VBT on this one is probably a better approximation of the reality
than assuming it always works. Thus we've queued [1] and [2] for 3.15
which should help.

[1] http://cgit.freedesktop.org/drm-intel/commit/?id=39fbc9c8f6765959b55e0b127dd5c57df5a47d67
[2] http://cgit.freedesktop.org/drm-intel/commit/?id=c675949ec58ca50d5a3ae3c757892f1560f6e896

>> Let's at least get this into -next for 3.16 and figure out whether the
>> drivers actually work now.
>
> I agree.

Agreed.


BR,
Jani.


-- 
Jani Nikula, Intel Open Source Technology Center