[Intel-gfx] [PATCH] drm/i915: Recognise non-VGA display devices

[Dave Airlie]

On Fri, Jan 21, 2011 at 10:25 AM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> On Fri, 21 Jan 2011 08:49:59 +1000, Dave Airlie <airlied at gmail.com> wrote:
>> On Fri, Jan 21, 2011 at 1:07 AM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
>> > Starting with SandyBridge (though possible with earlier hacked BIOSes),
>> > the BIOS may initialise the IGFX as secondary to a discrete GPU. Prior,
>> > it would simply disable the integrated GPU. In such a configuration, the
>> > IGFX is not a primary VGA controller and so should not take part in VGA
>> > arbitration.
>>
>> VGA arb shouldn't happen for any devices not VGA class, it shouldn't place the
>> devices into the arb list at all in this case.
>
> Right, it doesn't happen, but i915 also need not to throw an error when
> vgaarb rejects the device as being !DISPLAY_VGA.
>
> I'll try and update the comments to explain why I've chosen to handle it
> this way.

You could just ignore the error return, also vga arb and vga
switcheroo are very different
things, so they don't mean the same thing at all. So not sure why you
are touching
the switcheroo code here.

Or we could just fix the arbiter to not return anything on failure.

Dave.