[PATCH] ARM: kernel: document ARM CPUs clock-frequency property

[Lorenzo Pieralisi]

On Wed, Jun 19, 2013 at 11:27:50AM +0100, Florian Fainelli wrote:
> Hello Mark,
> 
> 2013/6/19 Mark Rutland <mark.rutland at arm.com>:
> > On Wed, Jun 19, 2013 at 10:47:17AM +0100, Florian Fainelli wrote:
> >> ARM CPU device tree nodes may contain an optional clock-frequency
> >> property, when set, this property must contain the CPU frequency in Hz,
> >> which is then used by the topology parsing code in
> >> arch/arm/kernel/topology.c to infer the CPU capacity.
> >
> > I see that arch/arm/kernel/topology.c does a pr_err when clock-frequency isn't
> > present. If we're documenting it as optional, should we not downgrade that or
> > remove it entirely?
> 
> Good question. I think it might be good to just dowgrade the error to
> a simple warning, we should clearly be fixing the binding if we have a
> device_type = "cpu" property but no clock-frequency property.

Well, this means that that pr_err will trigger as soon as the dts
updates hit the mainline, now probably it is silent because cpu nodes
for architectures with "arm,cortex-a15" as cpus miss device_type = "cpu".
ePAPR defines "clock-frequency" as required.

So either we downgrade it to optional or we are in for another slew of dts
updates, I am really looking forward to that. Certainly it has to be added
to the bindings.

Thoughts ?

Lorenzo