Re: [PATCH V2 1/2] PM / Domains: Introduce domain-performance-states binding

Rob Herring
2016-12-22T18:34:53Z

On Mon, Dec 12, 2016 at 04:26:18PM +0530, Viresh Kumar wrote:
> Some platforms have the capability to configure the performance state of
> their Power Domains. The performance levels are represented by positive
> integer values, a lower value represents lower performance state.
>
> The power-domains until now were only concentrating on the idle state
> management of the device and this needs to change in order to reuse the
> infrastructure of power domains for active state management.
>
> This patch adds binding to describe the performance states of a power
> domain.
>
> 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 node directly. Otherwise the
> consumers can define their requirements with help of other
> infrastructure, for example the OPP table.
>
> Signed-off-by: Viresh Kumar <viresh.kumar-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> ---
> .../devicetree/bindings/power/power_domain.txt | 69 ++++++++++++++++++++++
> 1 file changed, 69 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/power/power_domain.txt b/Documentation/devicetree/bindings/power/power_domain.txt
> index 723e1ad937da..a456e0dc04e0 100644
> --- a/Documentation/devicetree/bindings/power/power_domain.txt
> +++ b/Documentation/devicetree/bindings/power/power_domain.txt
> @@ -38,6 +38,40 @@ phandle arguments (so called PM domain specifiers) of length specified by the
> domain's idle states. In the absence of this property, the domain would be
> considered as capable of being powered-on or powered-off.
>
> +- domain-performance-states : A phandle of the performance states node, which
> + defines all the performance states associated with a power
> + domain.
> + The domain-performance-states property reflects the performance states of this
> + PM domain and not the performance states of the devices or sub-domains in the
> + PM domain. Devices and sub-domains have their own performance states, which
> + are dependent on the performance state of the PM domain.
> +
> +* PM domain performance states node
> +
> +This describes the performance states of a PM domain.
> +
> +Required properties:
> +- compatible: Allow performance states to express their compatibility. It should
> + be: "domain-performance-state".
> +
> +- Performance state nodes: This node shall have one or more "Performance State"
> + nodes.
> +
> +* Performance state node
> +
> +Required properties:
> +- performance-level: A positive integer value representing the performance level
> + associated with a performance state. The integer value '1' represents the
> + lowest performance level and the highest value represents the highest
> + performance level.
> +
> +Optional properties:
> +- domain-microvolt: voltage in micro Volts.
> +
> + A single regulator's voltage is specified with an array of size one or three.
> + Single entry is for target voltage and three entries are for <target min max>
> + voltages.
> +
> Example:
>
> power: power-controller@12340000 {
> @@ -118,4 +152,39 @@ The node above defines a typical PM domain consumer device, which is located
> inside a PM domain with index 0 of a power controller represented by a node
> with the label "power".
>
> +Optional properties:
> +- domain-performance-state: A phandle of a Performance state node.
> +
> +Example:
> +
> + parent: power-controller@12340000 {
> + compatible = "foo,power-controller";
> + reg = <0x12340000 0x1000>;
> + #power-domain-cells = <0>;
> + domain-performance-states = <&domain_perf_states>;
> + };
> +
> + domain_perf_states: performance_states {

If you want to have performance states for a domain in DT, then you need
to actually have a node for the domain in DT. Then this should be a
child of the domain. I wouldn't think non-CPU domain performance states
will be common across domains.

> + compatible = "domain-performance-state";
> + domain_perf_state1: pstate@1 {

A unit address should have a reg property.

> + performance-level = <1>;
> + domain-microvolt = <970000 975000 985000>;
> + };
> + domain_perf_state2: pstate@2 {
> + performance-level = <2>;
> + domain-microvolt = <1000000 1075000 1085000>;
> + };
> + domain_perf_state3: pstate@3 {
> + performance-level = <3>;
> + domain-microvolt = <1100000 1175000 1185000>;
> + };
> + }
> +
> + leaky-device@12350000 {
> + compatible = "foo,i-leak-current";
> + reg = <0x12350000 0x1000>;
> + power-domains = <&power 0>;
> + domain-performance-state = <&domain_perf_state2>;

domain-performance-state and domain-performance-states are too similar
in name. The property here should probably reflect the mode needed and
perhaps specific to the device. I assume a device will need multiple
states/modes.

Also, since you refer to the performance state node directly, I'm not
sure why you need the performance-level property.

Rob
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