linux-kernel - Re: [PATCH V3 2/7] PM / OPP: Introduce "domain-performance-state" binding to OPP nodes

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Date:   Mon, 27 Feb 2017 18:39:48 -0600
From:   Rob Herring <robh@...nel.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Rafael Wysocki <rjw@...ysocki.net>, ulf.hansson@...aro.org,
        Kevin Hilman <khilman@...aro.org>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        lina.iyer@...aro.org, rnayak@...eaurora.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH V3 2/7] PM / OPP: Introduce "domain-performance-state"
 binding to OPP nodes

On Fri, Feb 24, 2017 at 02:36:34PM +0530, Viresh Kumar wrote:
> If the consumers don't need the capability of switching to different
> domain performance states at runtime, then they can simply define their
> required domain performance state in their nodes directly.
> 
> But if the device needs the capability of switching to different domain
> performance states, as they may need to support different clock rates,
> then the per OPP node can be used to contain that information.
> 
> This patch introduces the domain-performance-state (already defined by
> Power Domain bindings) to the per OPP node.
> 

We already have OPP voltages, why are those not sufficient?

> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> Tested-by: Rajendra Nayak <rnayak@...eaurora.org>
> ---
>  Documentation/devicetree/bindings/opp/opp.txt | 64 +++++++++++++++++++++++++++
>  1 file changed, 64 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
> index 9f5ca4457b5f..7f6bb52521b6 100644
> --- a/Documentation/devicetree/bindings/opp/opp.txt
> +++ b/Documentation/devicetree/bindings/opp/opp.txt
> @@ -154,6 +154,15 @@ properties.
>  
>  - status: Marks the node enabled/disabled.
>  
> +- domain-performance-state: A positive integer value representing the minimum
> +  performance level (of the parent domain) required by the consumer as defined
> +  by ../power/power_domain.txt binding document. The OPP nodes can contain the
> +  "domain-performance-state" property, only if the device node contains a
> +  "power-domains" property. The OPP nodes aren't allowed to contain the
> +  "domain-performance-state" property partially, i.e. Either all OPP nodes in
> +  the OPP table have the "domain-performance-state" property or none of them
> +  have it.
> +
>  Example 1: Single cluster Dual-core ARM cortex A9, switch DVFS states together.
>  
>  / {
> @@ -528,3 +537,58 @@ Example 5: opp-supported-hw
>  		};
>  	};
>  };
> +
> +Example 7: domain-Performance-state:
> +(example: For 1GHz require domain state 1 and for 1.1 & 1.2 GHz require state 2)
> +
> +/ {
> +	cpu0_opp_table: opp_table0 {
> +		compatible = "operating-points-v2";
> +		opp-shared;
> +
> +		opp@...0000000 {
> +			opp-hz = /bits/ 64 <1000000000>;
> +			domain-performance-state = <1>;

Thinking about this some more, there's a problem here that you have no 
link to foo_domain. I guess that resides in the cpu's node?

Perhaps instead of a number, this should be a phandle to pstate@1. Then 
you just get the parent if you need to know the domain.

> +		};
> +		opp@...0000000 {
> +			opp-hz = /bits/ 64 <1100000000>;
> +			domain-performance-state = <2>;
> +		};
> +		opp@...0000000 {
> +			opp-hz = /bits/ 64 <1200000000>;
> +			domain-performance-state = <2>;
> +		};
> +	};
> +
> +	foo_domain: power-controller@...40000 {
> +		compatible = "foo,power-controller";
> +		reg = <0x12340000 0x1000>;
> +		#power-domain-cells = <0>;
> +
> +		performance-states {
> +			compatible = "domain-performance-state";
> +			pstate@1 {
> +				reg = <1>;
> +				domain-microvolt = <970000 975000 985000>;
> +			};
> +			pstate@2 {
> +				reg = <2>;
> +				domain-microvolt = <1000000 1075000 1085000>;
> +			};
> +		};
> +	}
> +
> +	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>;
> +		};
> +	};
> +};
> -- 
> 2.7.1.410.g6faf27b
>