[Mesa-dev] [PATCH 0/5] i965/gen9: Support fast clear on SRGB buffers

[Ben Widawsky]

On Wed, Nov 25, 2015 at 06:36:34PM +0100, Neil Roberts wrote:

[snip]

> 
> Sadly there is a second obstacle stopping window system buffers from
> using fast clears which as that they are always x-tiled and supposedly
> SKL doesn't support that. This is explicitly disabled in
> intel_tiling_supports_non_msrt_mcs. However if I remove that
> restriction I couldn't find any problems so it might just work to
> remove it.

In general I think the practice of, it seems to work so let's assume the docs
are incorrect, is not a sustainable thing to do. Generally we actually go the
opposite route or, we had no problems, but the docs say we can't do it - so
don't. If you feel the docs are probably incorrect, I'd suggest we file a spec
issue to get clarification.

My guess is that the likely scenario is X-tiled just wasn't validated, which
effectively means it's unsupported. However, the patch to just use X-tiled
wouldn't be a bad patch to have sitting around on the mailing list though for
people to get perf numbers with (if nothing else, maybe it will further the
current stalemate we have over my patch to always use Y-tiled).

> 
> All of my SKL fast clear patches are in a branch here:
> 
> https://github.com/bpeel/mesa/commits/skl-fast-clear
> 

-- 
Ben Widawsky, Intel Open Source Technology Center