Re: PMU node location

[Rob Herring <robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On 01/10/2013 07:47 AM, Michal Simek wrote:
> Hi Rob, Mark, Grant and others,
> 
> I want to check with you the location of ARM pmu node
> I see that
> 1) highbank and dbx5x0 have it in soc node
> 
> 2) vexpress and tegra have no main bus and pmu is in root like all
> others devices.
> (Any reason no to have main bus? Does it mean that there is no bus or
> that all
> devices are accessible?)

That seems really wrong in general. Any memory mapped device is on a bus
of some kind. I'm not sure the reasoning. Perhaps Stephen can explain.

> 3) omap2/omap3 have added pmu node to root node(mailing list)
> 
> 4) Just for completeness no platform has it in the bus.
> 
> 
> That's why I have obvious question what it is proper location for pmu node?

Obviously, highbank is the true and correct way. ;)

The pmu is part of the cpu, so it could be part of /cpus. That may cause
problems having non-cpu nodes and it would not get probed (although
technically that is a Linux problem and should not influence the DT).
Since it is not on a bus, then putting it at the top level probably
makes more sense than on a bus.

Rob

> 
> Thanks,
> Michal
>