[Mesa-dev] [PATCH 7/7] i965/gen7+: Implement fast color clears for MSAA buffers.

[Paul Berry]

On 4 December 2013 15:07, Chad Versace <chad.versace at linux.intel.com> wrote:

>
> bugget, verticeally, and vestically! oh my!
>

Wow, I wish I could say I did all those typos on purpose.  Those are
hilarious!

They're all fixed now.


>
> Patches 1-6 are
> Reviewed-by: Chad Versace <chad.versace at linux.intel.com>
>
> But this patch 7... If the user specifies an ill-aligned clear rectangle,
> does this code clear a slightly larger, well-aligned rectangle? In other
> words,
> will this clear pixels outside the user-specified clear rectangle? Local
> inspection of the code suggests so to me. But my global understanding of
> these codepaths is vague.
>

Ken is right in his response about this--partial fast clears never happen
because of the !partial_clear check, so the extra pixels that get cleared
are always outside the bounds of the buffer (and hence irrelevant).  Thanks
to tiling, there's no worry about overflowing into memory owned by other
regions--the extra pixels that get cleared always belong to tiles that
contain in-bounds pixels.  In theory I believe we could do partial clears
if we first verified that they were aligned, but (a) the bspec doesn't
recommend it, and (b) I doubt there would be much benefit, since
sufficiently aligned clears that don't clear the entire buffer are probably
quite rare.

I'll follow up with a patch that improves the comments to clarify this.
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