Re: [PATCH v4 2/2] dt: power: st: Provide bindings for ST's OPPs

From: Lee Jones
Date: Wed Aug 26 2015 - 08:06:54 EST

On Wed, 12 Aug 2015, Viresh Kumar wrote:

> On 11-08-15, 16:17, Lee Jones wrote:
> > This would work if we only had a single variable to contend with, but
> > what I showed you in my previous example is that we have 3 variables
> > to consider; cut (version), pcode and substrate.
> >
> > Using the two (simple) examples I provided, how would your suggestion
> > look in our case?
> So the solution I gave is for picking the microvolt based on pcode.
> The other two (cut, substrate) aren't about picking microvolt, but if
> the OPP is available or not. Right?

'pcode', 'cut' and 'substrate' all determine whether a given set of
OPPs an be used on the running platform. I do not believe that you
can differentiate between them.

> If these terms are generic enough, then we can add something similar
> to what you have added..

If it makes it easier, you can treat them as version numbers 2.2.1
<pcode.cut.substrate>, but I don't see how this can help. Obviously
this becomes more difficult when you add wild cards to the OPPs, where
a particular OPP would be suitable for all cuts for example.

If you still think you can come up with a generic method to lay out
CPUFreq OPP nodes that will satisfy all vendors and not be a mass of
10's of separate nodes, then great. Again, I'm struggling to see how
that might be possible.

What I believe we shouldn't do, is have this blocked forever for the
sake of adding a couple of vendor properties however.

Lee Jones
Linaro STMicroelectronics Landing Team Lead â Open source software for ARM SoCs
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