[Intel-gfx] [PATCH] drm/i915: Remove temporary allocation of dma addresses when rotating

[Chris Wilson]

Quoting Tvrtko Ursulin (2017-11-15 09:18:00)
> 
> On 14/11/2017 18:14, Chris Wilson wrote:
> > Honestly I think the page_iter cache is useful and likely to already
> > exist or be used shortly after a portion of the object is rotated.
> 
> How come? I thought CPU access to framebuffers is atypical nowadays.

But not entirely forgotten. It's the first, and sometimes, last thing a
client wires up. (Just yesterday mesa gained a patch for yet another
access path. Great.)

I also think it is of wider utility for the when the buffer gets reused
or new views. Your argument applies better to the wider aspect of the
futility of keeping caches around that may never be reused. And that is
worth improving, even more so if we can measure an impact.
-Chris