[PATCH v4 01/10] drm/fourcc: Add AFBC yuv fourccs for Mali

[Brian Starkey]

Hi,

On Mon, Mar 18, 2019 at 11:17:55AM +0100, Maarten Lankhorst wrote:

<snip>

> Hey..
> 
> There's a conflict with this patch and the merge of topic/hdr-formats, resulting in double definitions for Y210, Y410 and P010.
> 
> Worse still is that one has set has_alpha to true for Y41x and other to false.
> 
> ~Maarten
> 

Oh that's sad :-( I think this fell through the cracks on our side
when someone left our team. Also turns out I'm not subscribed to
igt-dev.

I see you commented the same on one of the previous patches, and that
there was some discussion of this on the test patches too.

I have been referring to Microsoft's page[1] as "the" source for these
formats, which does indeed call out Y410 as having 2 bits of alpha.
Our GPU expects alpha.

Was there a specific reason for opting to change the test instead of
the definition? Any way to get this changed now?

It doesn't seem that sensible for the kernel to call something Y410
which doesn't match an "existing" definition by the same name. If
alpha needs to be ignored on scanout, the alpha blend mode property
can be used (more archaeology - I see that was still giving CRC
failures, but that might be a "known issue" for all YUV on your HW?)

-Brian

[1] https://docs.microsoft.com/en-us/windows/desktop/medfound/10-bit-and-16-bit-yuv-video-formats#444-formats