[Intel-gfx] [PATCH] drm/i915: GFDT support for SNB/IVB

[Chris Wilson]

On Mon, Mar 04, 2013 at 03:51:11PM +0200, Ville Syrjälä wrote:
> On Sun, Mar 03, 2013 at 05:39:09PM +0000, Chris Wilson wrote:
> > On Sun, Mar 03, 2013 at 05:28:52PM +0100, Daniel Vetter wrote:
> > > The other thing was that I didn't manage to get things to work properly,
> > > leaving some random cachline dirt on the screen. Looking at your code, you
> > > add the gfdt flush to every ring_flush, whereas I've tried to be clever
> > > and only flushed after batches rendering to the frontbuffer. So probably a
> > > bug in my code, or a flush on a given ring doesn't flush out caches for
> > > one of the other engines.
> > 
> > Right, we have a formalized interface for flushes to scanout rather than
> > always flushing GFDT.
> 
> We do? Where's that?

A side-effect of the API for busy_ioctl() is that all caches for the bo
are flushed and any outstanding requests queued in order for the
bo to become unbusy in the near-future. This semantic was required for
GL query objects to eventually complete without futher interaction. It
also solved the problem of having to flush the scanout periodically on
gen4+ (and on gen3 if we enable the optimisation bit) and is so
enshrined into lore.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre