[Intel-gfx] [RFC] drm/i915/skl: Use plane update function from mmio flips

[Chris Wilson]

On Thu, Apr 23, 2015 at 09:15:41PM +0200, Daniel Vetter wrote:
> On Tue, Apr 21, 2015 at 01:18:57PM +0100, Tvrtko Ursulin wrote:
> > Interesting, well, I had a look around and this means all sorts of "trouble"
> > (refactoring) if proper wm param comparison is to be done.
> > 
> > Alternatively, in (more) cheating via embedding knowledge approach, then
> > rejecing a change in tiling is simple, but rotation is only known in plane
> > state and page flip is not able to compare old vs. new.
> > 
> > In fact, I don't even know if possible since plane properties and page flips
> > look disjoint, each living in it's own timeline. If sampled when flip is
> > queued it will be bad, if sampled with the flip then it is too late and/or
> > properly slow.
> 
> With atomic we can't do such tricks anymore anyway, we always have to
> recompute the full state. We'll we could set dirty bits and similar tricks
> to avoid recomputing some state and the corresponding setup, but imo that
> needs to come with performance data attached. And atm pageflips are
> limited to refresh rate.

And in a helper process/thread. Though we need to be sure that it
doesn't take more than a frame to queue a flip ;-)
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre