[Intel-gfx] [PATCH v3] drm/i915: add immutable zpos plane properties

[Maarten Lankhorst]

Op 16-04-2019 om 15:42 schreef Ville Syrjälä:
> On Tue, Apr 16, 2019 at 03:28:15PM +0200, Maarten Lankhorst wrote:
>> Op 16-04-2019 om 15:20 schreef Ville Syrjälä:
>>> On Sat, Apr 13, 2019 at 11:13:27AM +0000, Simon Ser wrote:
>>>> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>>>>
>>>> This adds basic immutable support for the zpos property. The zpos increases
>>>> from bottom to top: primary, sprites, cursor.
>>> I was thinking a bit about how we might go about testing this.
>>>
>>> We probably want a basic test that just checks that if any
>>> plane has a zpos prop then all planes should have it.
>> This would be a good test for BAT.
>>> A functional test would stack the planes up in some way and
>>> compare against a software rendered reference. IIRC there was 
>>> a zpos test case floating around but that depended on alpha
>>> blending which we don't necessarily have.
>> But with semi-overlapping planes you would accomplish the same, without alpha dependency.
>>
>> Something like this?
>>
>> [BG]   [Sprite 1]    [Cursor]
>>   [Primary]   [Sprite 2]
> Should probably be good enough. Though I was pondering is there a
> way to position an arbitraty number of planes such that the
> resulting picture has a visible region for every possible
> combination of planes?

n planes, width = width / (n + 1)

position = n * 3/4 * plane_width ? or something

If each plane has its own color, then it would work..

>> Perhaps primary fullscreen to prevent issues with hw that doesn't support partial planes?
> I guess. And maybe a second test that disables the primary
> so that we can also get the bg color into the picture?

I don't think we finalized the bg color api yet, else it would be good to have..