[Intel-gfx] [RFC v2] drm/i915: Android native sync support

[Chris Wilson]

On Wed, Jan 28, 2015 at 10:22:15AM +0100, Daniel Vetter wrote:
> On Mon, Jan 26, 2015 at 09:08:03AM +0000, Chris Wilson wrote:
> > On Mon, Jan 26, 2015 at 08:52:39AM +0100, Daniel Vetter wrote:
> > > I think the problem will be platforms that want full explicit fence (like
> > > android) but allow delayed creation of the fence fd from a gl sync object
> > > (like the android egl extension allows).
> > > 
> > > I'm not sure yet how to best expose that really since just creating a
> > > fence from the implicit request attached to the batch might upset the
> > > interface purists with the mix in implicit and explicit fencing ;-) Hence
> > > why I think for now we should just do the eager fd creation at execbuf
> > > until ppl scream (well maybe not merge this patch until ppl scream ...).
> > 
> > Everything we do is buffer centric. Even in the future with random bits
> > of memory, we will still use buffers behind the scenes. From an
> > interface perspective, it is clearer to me if we say "give me a fence for
> > this buffer". Exactly the same way as we say "is this buffer busy" or
> > "wait on this buffer". The change is that we now hand back an fd to slot
> > into an event loop. That, to me, is a much smaller evolutionary step of
> > the existing API, and yet more versatile than just attaching one to the
> > execbuf.
> 
> The problem is that big parts of the world do not subscribe to that buffer
> centric view of gfx. Imo since those parts will be the primary users of
> this interface we should try to fit their ideas as much as feasible. Later
> on (if we need it) we can add some glue to tie in the buffer-centric
> implicit model with the explicit model.

They won't be using execbuffer either. So what's your point?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre