[RFC] drm: add support for tiled/compressed/etc modifier in addfb2

[Daniel Stone]

Hi,

On 12 December 2014 at 18:00, Ville Syrjälä <ville.syrjala at linux.intel.com>
wrote:
>
> On Fri, Dec 12, 2014 at 05:11:50PM +0000, Daniel Stone wrote:
> > If you're doing it through GL, you've already lost. Either you're doing
> > some magic behind the user's back to bind multi-planar dmabuf-EGLImages
> to
> > TEXTURE_2D with RGB sampling, or you're binding to TEXTURE_EXTERNAL_OES,
> > which forces you to use linear/nearest filtering. Even if you do use
> > TEXTURE_2D binding, the EGLImage import spec does exactly the same as
> > what's suggested here, and treats them as hints, which the implementation
> > can use or ignore. So far I don't know of any implementation which
> doesn't
> > ignore them.
>
> Well anyone who is serious about quality ought to handle that stuff.
> Or at least make sure both GL/whatever and planes ignore the hints in
> the same way. So if you GL implementation is lax then you anyway need
> to have some driver/hardware specific knowledge to know which way to go
> when using the plane path to get matching output.
>

Anyone who's serious about quality and is also using GL for video, is not
serious about quality. Or accurate timing.


> > > But for some simpler cases like Xv it would seem perfectly OK to use
> the
> > > less strict rules. Well, unless someone implements Xv in a way that can
> > > also transparently switch between display planes and GL/software
> rendering.
> >
> > Well sure, if you absolutely want to ensure it works, you're going to
> need
> > some kind of query. Maybe, if the range/chroma-siting ones were part of a
> > bitmask, you could steal the top bit to mark that the hints are actually
> > requirements, and to fail if you can't respect the hints.
>
> I was more thinking of some global "I want exactly what I said" kind
> of knob. Maybe as a client cap type of thingy.
>

I like the idea of keeping it local to the chroma-siting/range hints,
because it makes it far more clear exactly what it affects.

Cheers,
Daniel
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