[PATCH 0/3] drm: panfrost: Coherency support

[Rob Herring]

On Wed, Sep 16, 2020 at 11:04 AM Alyssa Rosenzweig
<alyssa.rosenzweig at collabora.com> wrote:
>
> > So I get a performance regression with the dma-coherent approach, even if it's
> > clearly the cleaner.
>
> That's bizarre -- this should really be the faster of the two.

Coherency may not be free. CortexA9 had something like 4x slower
memcpy if SMP was enabled as an example. I don't know if there's
anything going on like that specifically here. If there's never any
CPU accesses mixed in with kmscube, then there would be no benefit to
coherency.

Rob