[PATCH 1/3] arm64: topology: Add support for topology DT bindings

[broonie@kernel.org (Mark Brown)]

On Thu, Mar 20, 2014 at 11:26:50AM +0000, Lorenzo Pieralisi wrote:
> On Wed, Mar 19, 2014 at 06:02:17PM +0000, Mark Brown wrote:
> > +#ifdef CONFIG_OF

> This ifdef can be removed, CONFIG_OF is always selected for arm64 and
> the !CONFIG_OF path

This has been present since the very first time these patches were
posted but hasn't been mentioned as being a problem previously.

> > +#else
> > +static inline int parse_dt_topology(void) { return 0; }
> > +#endif

> is wrong, it should return failure. You should remove the CONFIG_OF
> ifdeffery.

Yup.  It actually won't affect the behaviour at present though - since
it won't do anything the result will be just the same as if we return an
error and reset.

Given ACPI (which really looks like it's going to happen at some point
and presumably make OF optional) I'm not sure removing the handling of
OF is actually constructive but whatever, it's done now...

> > +			if (leaf) {
> > +				ret = parse_core(c, cluster_id, core_id++);
> > +				if (ret != 0) {
> > +					return ret;
> > +				}

> WARNING: braces {} are not necessary for single statement blocks
> #139: FILE: arch/arm64/kernel/topology.c:132:

Like I say I don't think checkpatch is being helpful on this one, the
code looks worse.  Again, whatever.

> We still have a problem here. If the topology does not contain bindings
> for some cpu nodes, parse_cluster() does not fail and we end up with an
> incomplete topology. We have two choices: either we check the topology

Hrm, looking at the topology binding it doesn't specificially require
that the topology be complete.  I can see why you would want that.

> I'd rather do it here, in preparation for MPIDR_EL1 fallback solution
> (where there will always be topology information configured and the register
> will always be there in all its glory).

To be honest at this point I think what I want to do is go back to the
original approach of layering DT on top of MPIDR.  MPIDR is smaller and
simpler code so seems more likely to make progress.  I really do expect
that for a very large proportion of systems it'll be sufficient.
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