Re: [PATCH 4/7] drm/meson: plane: add support for AFBC mode for OSD1 plane

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Oct 11, 2019 at 12:56 PM Brian Starkey <Brian.Starkey@arm.com> wrote:
>
> Hi,
>
> On Fri, Oct 11, 2019 at 11:14:43AM +0200, Neil Armstrong wrote:
> > Hi Brian,
> >
> > On 11/10/2019 10:41, Brian Starkey wrote:

> > > Are you sure the GPU supports other orders? I think any Arm driver
> > > will only be producing DRM_FORMATs with "BGR" order e.g. ABGR888>
> > > I'm not convinced the GPU HW actually supports any other order, but
> > > it's all rather confusing with texture swizzling. What I can tell you
> > > for sure is that it _does_ support BGR order (in DRM naming
> > > convention).
> >
> > Well, since the Bifrost Mali blobs are closed-source and delivered
> > by licensees, it's hard to define what is supported from a closed
> > GPU HW, closed SW implementation to a closed pixel format implementation.
> >
>
> I hear you. IMO the only way to make any of this clear is to publish
> reference data and tests which make sure implementations match each
> other. It's something I'm trying to make happen.

*cough* igt test with crc/writeback validation *cough*

And you don't even need anything that actually compresses. All you
need is the minimal enough AFBC knowledge to set up the metadata that
everything is uncompressed. We're doing that for our intel compression
formats already, and it works great in making sure that we have
end-to-end agreement on all the bits and ordering and everything. Ofc
it doesn't validate the decoder, but that's not really igts job.
Should be possible to convince ARM to release that (as open source, in
igt), since it would be fairly valuable for the entire ecosystem here
...
-Daniel

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

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