Re: [RFC PATCH 1/2] PM / OPP: add support to specify phandle of another node for OPP

[Stephen Warren <swarren@wwwdotorg.org>]

On 08/20/2013 04:00 AM, Sudeep KarkadaNagesha wrote:
...
> Until we get more feedback and agreement on new proposal can we have
> this simple amendment in this patch to the existing binding ? Since the
> new proposal[1] is backward compatible(this patch adding support for
> option#5 to existing option#1), we will have to add support for other
> binding options in [1] later.
> 
> This is needed to support shared OPPs with simple/single OPP profile
> and also to fix the broken and unused binding
> @Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt
> 
> Regards,
> Sudeep
> 
> [1] http://www.spinics.net/lists/cpufreq/msg06563.html

Presumably the desire for cpu1's node to say "go look at cpu0's node for
OPP" is because they share OPPs. Don't they share OPPs because they are
parts of the same device - that device being the CPU complex. As such,
why not define the OPPs in /cpus rather than in each of /cpus/cpuN?

Of course, that doesn't help if there are separate CPU and GPU nodes
that just happen to have the same set of OPPs and you want to share them
to save DT space. Is that at all likely?

I'd suggest/bike-shed that operating-points-device is not the correct
property name; it somehow implies that the other device actively defines
the OPPs for this device, rather than just happening to have the same
OPPs. Perhaps "operating-points-identical-to"?