Re: [PATCH 3/7] dt-bindings: power: Convert domain-idle-states bindings to json-schema

[Ulf Hansson <ulf.hansson@linaro.org>]

On Tue, 3 Mar 2020 at 18:02, Rob Herring <robh@kernel.org> wrote:
>
> On Tue, Mar 03, 2020 at 04:07:45PM +0100, Ulf Hansson wrote:
> > While converting to the json-schema, let's also take the opportunity to
> > further specify/clarify some more details about the DT binding.
> >
> > For example, let's define the label where to put the states nodes, set a
> > pattern for nodename of the state nodes and finally add an example.
> >
> > Fixes: a3f048b5424e ("dt: psci: Update DT bindings to support hierarchical PSCI states")
> > Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> > ---
> >  .../devicetree/bindings/arm/psci.yaml         |  2 +-
> >  .../bindings/power/domain-idle-state.txt      | 33 ---------
> >  .../bindings/power/domain-idle-state.yaml     | 67 +++++++++++++++++++
> >  .../bindings/power/power-domain.yaml          | 22 +++---
> >  .../bindings/power/power_domain.txt           |  2 +-
> >  5 files changed, 79 insertions(+), 47 deletions(-)
> >  delete mode 100644 Documentation/devicetree/bindings/power/domain-idle-state.txt
> >  create mode 100644 Documentation/devicetree/bindings/power/domain-idle-state.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/arm/psci.yaml b/Documentation/devicetree/bindings/arm/psci.yaml
> > index 540211a080d4..0bc3c43a525a 100644
> > --- a/Documentation/devicetree/bindings/arm/psci.yaml
> > +++ b/Documentation/devicetree/bindings/arm/psci.yaml
> > @@ -123,7 +123,7 @@ properties:
> >        to mandate it.
> >
> >        [3] Documentation/devicetree/bindings/power/power_domain.txt
> > -      [4] Documentation/devicetree/bindings/power/domain-idle-state.txt
> > +      [4] Documentation/devicetree/bindings/power/domain-idle-state.yaml
> >
> >    power-domains:
> >      $ref: '/schemas/types.yaml#/definitions/phandle-array'
> > diff --git a/Documentation/devicetree/bindings/power/domain-idle-state.txt b/Documentation/devicetree/bindings/power/domain-idle-state.txt
> > deleted file mode 100644
> > index eefc7ed22ca2..000000000000
> > --- a/Documentation/devicetree/bindings/power/domain-idle-state.txt
> > +++ /dev/null
> > @@ -1,33 +0,0 @@
> > -PM Domain Idle State Node:
> > -
> > -A domain idle state node represents the state parameters that will be used to
> > -select the state when there are no active components in the domain.
> > -
> > -The state node has the following parameters -
> > -
> > -- compatible:
> > -     Usage: Required
> > -     Value type: <string>
> > -     Definition: Must be "domain-idle-state".
> > -
> > -- entry-latency-us
> > -     Usage: Required
> > -     Value type: <prop-encoded-array>
> > -     Definition: u32 value representing worst case latency in
> > -                 microseconds required to enter the idle state.
> > -                 The exit-latency-us duration may be guaranteed
> > -                 only after entry-latency-us has passed.
> > -
> > -- exit-latency-us
> > -     Usage: Required
> > -     Value type: <prop-encoded-array>
> > -     Definition: u32 value representing worst case latency
> > -                 in microseconds required to exit the idle state.
> > -
> > -- min-residency-us
> > -     Usage: Required
> > -     Value type: <prop-encoded-array>
> > -     Definition: u32 value representing minimum residency duration
> > -                 in microseconds after which the idle state will yield
> > -                 power benefits after overcoming the overhead in entering
> > -i                the idle state.
> > diff --git a/Documentation/devicetree/bindings/power/domain-idle-state.yaml b/Documentation/devicetree/bindings/power/domain-idle-state.yaml
> > new file mode 100644
> > index 000000000000..27da43076b85
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/power/domain-idle-state.yaml
> > @@ -0,0 +1,67 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/power/domain-idle-state.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: PM Domain Idle States binding description
> > +
> > +maintainers:
> > +  - Ulf Hansson <ulf.hansson@linaro.org>
> > +
> > +description:
> > +  A domain idle state node represents the state parameters that will be used to
> > +  select the state when there are no active components in the PM domain.
> > +
> > +properties:
> > +  $nodename:
> > +    const: domain-idle-states
> > +
> > +patternProperties:
> > +  "^(cpu|cluster|domain)-":
> > +    type: object
> > +    description:
> > +      Each state node represents a domain idle state description.
> > +
> > +    properties:
> > +      compatible:
> > +        const: domain-idle-state
> > +
> > +      entry-latency-us:
> > +        $ref: /schemas/types.yaml#/definitions/uint32
>
> You don't need a type because the core schema defines it for all
> standard units.

Okay, I noticed some skips this, but wanted rather to clear and fuzzy.

In any case, yes, let's remove it.

>
> > +        description:
> > +          The worst case latency in microseconds required to enter the idle
> > +          state. Note that, the exit-latency-us duration may be guaranteed only
> > +          after the entry-latency-us has passed.
> > +
> > +      exit-latency-us:
> > +        $ref: /schemas/types.yaml#/definitions/uint32
> > +        description:
> > +          The worst case latency in microseconds required to exit the idle
> > +          state.
> > +
> > +      min-residency-us:
> > +        $ref: /schemas/types.yaml#/definitions/uint32
> > +        description:
> > +          The minimum residency duration in microseconds after which the idle
> > +          state will yield power benefits, after overcoming the overhead while
> > +          entering the idle state.
> > +
> > +    required:
> > +      - compatible
> > +      - entry-latency-us
> > +      - exit-latency-us
> > +      - min-residency-us
>
>        additionalProperties: false
>
> Do we have cases of adding additional properties?

I might, but I am not sure what's the correct way to deal with that.

What I am wondering about is the "arm,psci-suspend-param" property,
currently defined as part of the PSCI bindings (psci.yaml).

I am not sure that's correct to define it as a PSCI binding. Shouldn't
it rather be a part of the idle state bindings (idle-states.yaml) and
the domain idle states binding ($subject patch)?

What do you think?

In any case, we probably want to fix this on top, if we should care.

>
> I can fix these up when applying.

Thanks a lot!

Kind regards
Uffe