Re: [PATCH v5 02/15] dt: psci: Update DT bindings to support hierarchical PSCI states

[Rob Herring <robh+dt@kernel.org>]

On Mon, Dec 30, 2019 at 8:44 AM Ulf Hansson <ulf.hansson@linaro.org> wrote:
>
> Update PSCI DT bindings to allow to represent idle states for CPUs and the
> CPU topology, by using a hierarchical layout. Primarily this is done by
> re-using the existing DT bindings for PM domains [1] and for PM domain idle
> states [2].
>
> Let's also add an example into the document for the PSCI DT bindings, to
> clearly show the new hierarchical based layout. The currently supported
> flattened layout, is already described in the ARM idle states bindings [3],
> so let's leave that as is.
>
> [1] Documentation/devicetree/bindings/power/power_domain.txt
> [2] Documentation/devicetree/bindings/power/domain-idle-state.txt
> [3] Documentation/devicetree/bindings/arm/idle-states.txt
>
> Co-developed-by: Lina Iyer <lina.iyer@linaro.org>
> Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---
>
> Changes in v5:
>         - None.

First I'm seeing this as the DT list was not copied. The example has
problems when running 'make dt_binding_check':

Documentation/devicetree/bindings/arm/psci.example.dt.yaml: cpu@0:
compatible: Additional items are not allowed ('arm,armv8' was
unexpected)
Documentation/devicetree/bindings/arm/psci.example.dt.yaml: cpu@0:
compatible: ['arm,cortex-a53', 'arm,armv8'] is too long
Documentation/devicetree/bindings/arm/psci.example.dt.yaml: cpu@1:
compatible: Additional items are not allowed ('arm,armv8' was
unexpected)
Documentation/devicetree/bindings/arm/psci.example.dt.yaml: cpu@1:
compatible: ['arm,cortex-a57', 'arm,armv8'] is too long

'arm,armv8' is only valid for s/w models.

Documentation/devicetree/bindings/arm/psci.example.dt.yaml:
idle-states: cluster-retention:compatible:0: 'arm,idle-state' was
expected
Documentation/devicetree/bindings/arm/psci.example.dt.yaml:
idle-states: cluster-power-down:compatible:0: 'arm,idle-state' was
expected

The last 2 are due to my conversion of the idle-states binding which
is in my tree now. Probably need to add 'domain-idle-state' as a
compatible at a minimum. It looks like domain-idle-state.txt is pretty
much the same as arm/idle-state.txt, so we should perhaps merge them.

There's some bigger issues though.

> ---
>  .../devicetree/bindings/arm/cpus.yaml         |  15 +++
>  .../devicetree/bindings/arm/psci.yaml         | 104 ++++++++++++++++++
>  2 files changed, 119 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/arm/cpus.yaml b/Documentation/devicetree/bindings/arm/cpus.yaml
> index c23c24ff7575..7a9c3ce2dbef 100644
> --- a/Documentation/devicetree/bindings/arm/cpus.yaml
> +++ b/Documentation/devicetree/bindings/arm/cpus.yaml
> @@ -242,6 +242,21 @@ properties:
>
>        where voltage is in V, frequency is in MHz.
>
> +  power-domains:
> +    $ref: '/schemas/types.yaml#/definitions/phandle-array'
> +    description:
> +      List of phandles and PM domain specifiers, as defined by bindings of the
> +      PM domain provider (see also ../power_domain.txt).
> +
> +  power-domain-names:
> +    $ref: '/schemas/types.yaml#/definitions/string-array'
> +    description:
> +      A list of power domain name strings sorted in the same order as the
> +      power-domains property.
> +
> +      For PSCI based platforms, the name corresponding to the index of the PSCI
> +      PM domain provider, must be "psci".
> +
>    qcom,saw:
>      $ref: '/schemas/types.yaml#/definitions/phandle'
>      description: |
> diff --git a/Documentation/devicetree/bindings/arm/psci.yaml b/Documentation/devicetree/bindings/arm/psci.yaml
> index 7abdf58b335e..8ef85420b2ab 100644
> --- a/Documentation/devicetree/bindings/arm/psci.yaml
> +++ b/Documentation/devicetree/bindings/arm/psci.yaml
> @@ -102,6 +102,34 @@ properties:
>        [1] Kernel documentation - ARM idle states bindings
>          Documentation/devicetree/bindings/arm/idle-states.txt
>
> +  "#power-domain-cells":

This is wrong because you are saying the /psci node should have these
properties. You need to define the child nodes (at least a pattern you
can match on) and put these properties there.

> +    description:
> +      The number of cells in a PM domain specifier as per binding in [3].
> +      Must be 0 as to represent a single PM domain.
> +
> +      ARM systems can have multiple cores, sometimes in an hierarchical
> +      arrangement. This often, but not always, maps directly to the processor
> +      power topology of the system. Individual nodes in a topology have their
> +      own specific power states and can be better represented hierarchically.
> +
> +      For these cases, the definitions of the idle states for the CPUs and the
> +      CPU topology, must conform to the binding in [3]. The idle states
> +      themselves must conform to the binding in [4] and must specify the
> +      arm,psci-suspend-param property.
> +
> +      It should also be noted that, in PSCI firmware v1.0 the OS-Initiated
> +      (OSI) CPU suspend mode is introduced. Using a hierarchical representation
> +      helps to implement support for OSI mode and OS implementations may choose
> +      to mandate it.
> +
> +      [3] Documentation/devicetree/bindings/power/power_domain.txt
> +      [4] Documentation/devicetree/bindings/power/domain-idle-state.txt
> +
> +  power-domains:
> +    $ref: '/schemas/types.yaml#/definitions/phandle-array'
> +    description:
> +      List of phandles and PM domain specifiers, as defined by bindings of the
> +      PM domain provider.

A schema for 'domain-idle-states' property is missing.

>
>  required:
>    - compatible
> @@ -160,4 +188,80 @@ examples:
>        cpu_on = <0x95c10002>;
>        cpu_off = <0x95c10001>;
>      };
> +
> +  - |+
> +
> +    // Case 4: CPUs and CPU idle states described using the hierarchical model.
> +
> +    cpus {
> +      #size-cells = <0>;
> +      #address-cells = <1>;
> +
> +      CPU0: cpu@0 {
> +        device_type = "cpu";
> +        compatible = "arm,cortex-a53", "arm,armv8";
> +        reg = <0x0>;
> +        enable-method = "psci";
> +        power-domains = <&CPU_PD0>;
> +        power-domain-names = "psci";
> +      };
> +
> +      CPU1: cpu@1 {
> +        device_type = "cpu";
> +        compatible = "arm,cortex-a57", "arm,armv8";
> +        reg = <0x100>;
> +        enable-method = "psci";
> +        power-domains = <&CPU_PD1>;
> +        power-domain-names = "psci";
> +      };
> +
> +      idle-states {
> +
> +        CPU_PWRDN: cpu-power-down {
> +          compatible = "arm,idle-state";
> +          arm,psci-suspend-param = <0x0000001>;
> +          entry-latency-us = <10>;
> +          exit-latency-us = <10>;
> +          min-residency-us = <100>;
> +        };
> +
> +        CLUSTER_RET: cluster-retention {
> +          compatible = "domain-idle-state";
> +          arm,psci-suspend-param = <0x1000011>;
> +          entry-latency-us = <500>;
> +          exit-latency-us = <500>;
> +          min-residency-us = <2000>;
> +        };
> +
> +        CLUSTER_PWRDN: cluster-power-down {
> +          compatible = "domain-idle-state";
> +          arm,psci-suspend-param = <0x1000031>;
> +          entry-latency-us = <2000>;
> +          exit-latency-us = <2000>;
> +          min-residency-us = <6000>;
> +        };
> +      };
> +    };
> +
> +    psci {
> +      compatible = "arm,psci-1.0";
> +      method = "smc";
> +
> +      CPU_PD0: cpu-pd0 {
> +        #power-domain-cells = <0>;
> +        domain-idle-states = <&CPU_PWRDN>;
> +        power-domains = <&CLUSTER_PD>;
> +      };
> +
> +      CPU_PD1: cpu-pd1 {
> +        #power-domain-cells = <0>;
> +        domain-idle-states =  <&CPU_PWRDN>;
> +        power-domains = <&CLUSTER_PD>;
> +      };
> +
> +      CLUSTER_PD: cluster-pd {
> +        #power-domain-cells = <0>;
> +        domain-idle-states = <&CLUSTER_RET>, <&CLUSTER_PWRDN>;
> +      };
> +    };
>  ...
> --
> 2.17.1
>