[PATCH 2/3] ARM: mm: add support for HW coherent systems in PL310

Thomas Petazzoni thomas.petazzoni at free-electrons.com
Tue May 6 03:07:22 PDT 2014

Dear Catalin Marinas,

On Wed, 9 Apr 2014 15:06:25 +0100, Catalin Marinas wrote:

> > In fact, I'm not sure using a separate compatible string is possible,
> > because there are situations where the hardware platform may be I/O
> > coherent, and some situations where it is not the case. For example, in
> > the current kernel, the platform is I/O coherent when CONFIG_SMP is
> > enabled, but not I/O coherent when CONFIG_SMP is disabled. And it's the
> > same hardware platform, so same Device Tree in both cases.
> I think Russell has a better solution in his L2 cache cleanup series.
> Patch 18/44 introduces a .fixup function which takes the outer_cache_fns
> pointer and that's a place where your code can check whether coherency
> is present or not (and turn .sync into NULL).

I had a look at the .fixup proposal, but I don't see how a .fixup
function, which is completely internal to the L2 cache driver, could
guess whether the system is coherent or not.

Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering

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