[Mesa-dev] [PATCH] dri2: Insert a synchronisation point for glXWaitX

[Chris Wilson]

On Wed, Aug 17, 2016 at 12:13:23PM -0400, Adam Jackson wrote:
> On Wed, 2016-08-17 at 08:17 -0700, Eric Anholt wrote:
>  
> > All I'm saying is that it's the thing that was intentionally used for
> > this purpose in DRI1 and early DRI2, and maybe if it works we shouldn't
> > just accidentally drop it in a refactor.
> 
> I don't see how the patch in this thread does that. I confess I've been
> looped in on this somewhat late, so if there's another thread I should be
> looking at for context...

By calling invalidate on the drawable, before the backend will use the
surface (either as a texture or as a renderable) it will do a
DRI2GetBuffers() round trip. (It is also likely that the buffer will
have been invalidated in the meantime and alreadly pending the round
trip.) That provides the server with a definite point at which it can
insert a synchronisation barrier.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre