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Subject: Re: [PATCH V4 1/9] PM / OPP: Allow OPP table to be used for
 power-domains
To: Viresh Kumar <viresh.kumar@linaro.org>,
        Rafael Wysocki <rjw@rjwysocki.net>, ulf.hansson@linaro.org,
        Kevin Hilman <khilman@linaro.org>, Viresh Kumar <vireshk@kernel.org>,
        Nishanth Menon <nm@ti.com>, Stephen Boyd <sboyd@codeaurora.org>
References: <cover.1490001099.git.viresh.kumar@linaro.org>
 <e772e67a5445319bb8e0f312846ace666adc097f.1490001099.git.viresh.kumar@linaro.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>, linaro-kernel@lists.linaro.org,
        linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
        Vincent Guittot <vincent.guittot@linaro.org>, robh+dt@kernel.org,
        lina.iyer@linaro.org, rnayak@codeaurora.org,
        devicetree@vger.kernel.org
From: Sudeep Holla <sudeep.holla@arm.com>
Organization: ARM
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Date: Wed, 12 Apr 2017 18:05:30 +0100
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On 20/03/17 09:32, Viresh Kumar wrote:
[...]

> +
> +Example 7: domain-Performance-state:
> +(example: For 1GHz require domain state 1 and for 1.1 & 1.2 GHz require state 2)
> +
> +/ {
> +	domain_opp_table: opp_table0 {
> +		compatible = "operating-points-v2";
> +
> +		opp@1 {
> +			domain-performance-state = <1>;
> +			opp-microvolt = <975000 970000 985000>;
> +		};
> +		opp@2 {
> +			domain-performance-state = <2>;
> +			opp-microvolt = <1075000 1000000 1085000>;
> +		};
> +	};
> +
> +	foo_domain: power-controller@12340000 {
> +		compatible = "foo,power-controller";
> +		reg = <0x12340000 0x1000>;
> +		#power-domain-cells = <0>;
> +		operating-points-v2 = <&domain_opp_table>;
> +	}
> +
> +	cpu0_opp_table: opp_table1 {
> +		compatible = "operating-points-v2";
> +		opp-shared;
> +
> +		opp@1000000000 {
> +			opp-hz = /bits/ 64 <1000000000>;
> +			domain-performance-state = <1>;
> +		};
> +		opp@1100000000 {
> +			opp-hz = /bits/ 64 <1100000000>;
> +			domain-performance-state = <2>;
> +		};
> +		opp@1200000000 {
> +			opp-hz = /bits/ 64 <1200000000>;
> +			domain-performance-state = <2>;
> +		};
> +	};
> +
> +	cpus {
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +
> +		cpu@0 {
> +			compatible = "arm,cortex-a9";
> +			reg = <0>;
> +			clocks = <&clk_controller 0>;
> +			clock-names = "cpu";
> +			operating-points-v2 = <&cpu0_opp_table>;
> +			power-domains = <&foo_domain>;
> +		};
> +	};
> +};


Thinking more about this above example, I think you need more
explanation. So in the above case you have cpu with clock controller,
power-domain and the OPP table info, I can think of few things that need
to be explicit:

1. How does the precedence look like ?

2. Since power-domains with OPP table control the performance state, do
   we ignore clock and operating-points-v2 in the above case completely?

3. Will the power-domain drive the OPP ?

-- 
Regards,
Sudeep