Re: [PATCH] drm/i915: inverted brightness quirk for HP 2000 Notebook

[Jani Nikula <jani.nikula@intel.com>]

On Wed, 28 Aug 2013, Daniel Vetter <daniel@ffwll.ch> wrote:
> On Wed, Aug 28, 2013 at 7:38 PM, Rodrigo Vivi <rodrigo.vivi@gmail.com> wrote:
>> 01.org forum: https://01.org/linuxgraphics/node/199
>>
>> Slot:  00:02.0
>> Class: VGA compatible controller [0300]
>> Vendor:    Intel Corporation [8086]
>> Device:    2nd Generation Core Processor Family Integrated Graphics Controller [0106]
>> SVendor:   Hewlett-Packard Company [103c]
>> SDevice:   Device [1854]
>> Rev:       09
>>
>> Reported-by: Laurent Chardon <laurent.chardon@gmail.com>
>> Cc: Jani Nikula <jani.nikula@intel.com>
>> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
>
> All the inverted brightness machines we've seen have been gen4 and
> Acer/Packard Bell. I suspect there's something amiss in our backlight
> handling and at least for current platforms I don't want to merge
> quirks before we've reasonably proven that we really need them. Which
> means someone should show that Windows has specific code for this HP
> laptop first ...

Agreed. I'd be wary of adding inverted backlight quirks for anything
other than gen4 Acers (or their other brands).

> One thing I remember is that there's a linearization table in the vbt
> somewhere, maybe that does the trick. Or we simply race our driver
> against something in the firmware and inverting the brightness here
> cures that.

If you get the reporter to dump the i915_opregion file from debugfs, I
could check the table.

Cheers,
Jani.



> -Daniel
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch