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Re: [PATCH V3 0/7] PM / Domains: Implement domain performance states

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  Re: [PATCH V3 0/7] PM / Domains: Implement domain performance states Kevin Hilman <khilman@baylibre.com> - 2017-03-10 21:40 +0100
    Re: [PATCH V3 0/7] PM / Domains: Implement domain performance states Viresh Kumar <viresh.kumar@linaro.org> - 2017-03-13 11:50 +0100

#1598077 — Re: [PATCH V3 0/7] PM / Domains: Implement domain performance states

Viresh Kumar <viresh.kumar@linaro.org> writes:

> This series contain V3 of both the bindings and the code that implement
> them. They were sent separately earlier.
>
> Some platforms have the capability to configure the performance state of
> their power domains. The process of configuring the performance state is
> pretty much platform dependent and we may need to work with a wide range
> of configurables.  For some platforms, like Qcom, it can be a positive
> integer value alone, while in other cases it can be voltage levels, etc.

Why limit it to just voltage levels.

As I suggested earlier, I think this should use OPPs.  Remember that a
PM domain is not limited to a hardware power domain, but is just a
grouping mechanism for devices that share some PM properties.  As
mentioned by Geert, this can also be a clock domain, where frequencies
would make sense as well.  One can imagine using this type of PM domain
to manage an interconnect/bus which has scalable voltage/frequencies as
well.

Kevin

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#1599193

On 10-03-17, 12:38, Kevin Hilman wrote:
> Why limit it to just voltage levels.
> 
> As I suggested earlier, I think this should use OPPs.  Remember that a
> PM domain is not limited to a hardware power domain, but is just a
> grouping mechanism for devices that share some PM properties.  As
> mentioned by Geert, this can also be a clock domain, where frequencies
> would make sense as well.  One can imagine using this type of PM domain
> to manage an interconnect/bus which has scalable voltage/frequencies as
> well.

Okay, I tried to do that change today and am blocked a bit right now.

The OPP core and all of its APIs/interfaces have dependency on the
"struct device" for their working. It gets the of_node from it, stores
the device pointer to manage cases where multiple devices share OPP
table, uses it to get clk and regulators.

But the "genpd" structure doesn't have a 'struct device' associated
with it. How should I make both of them work together?

I tried to create separate helpers that don't accept 'dev', but that
is also not good.  Just too much redundant code everywhere.

Would creating a 'dev' structure within 'generic_pm_domain' be
acceptable? Or should we ask the domain-drivers to call something like
of_genpd_parse_idle_states(), with a fake 'dev' structure which has
its of_node initialized? Or maybe move that hack within the OPP-core
API, which can create a dev structure at runtime for the genpd passed
to it and get the OPP table out?

-- 
viresh

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