linux-kernel - Re: [PATCH v2 1/2] dt-bindings: connector: Add child nodes for multiple PD capabilities

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Message-ID: <CAL_JsqLjAooY27pG4GQHRdpiB_=0RCYrkKOjzAvmvz=5yU71Og@mail.gmail.com>
Date:   Wed, 22 Nov 2023 08:36:19 -0700
From:   Rob Herring <robh@...nel.org>
To:     Kyle Tso <kyletso@...gle.com>
Cc:     krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        linux@...ck-us.net, heikki.krogerus@...ux.intel.com,
        gregkh@...uxfoundation.org, badhri@...gle.com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org
Subject: Re: [PATCH v2 1/2] dt-bindings: connector: Add child nodes for
 multiple PD capabilities

On Wed, Oct 18, 2023 at 12:19 PM Kyle Tso <kyletso@...gle.com> wrote:
>
> On Tue, Aug 22, 2023 at 12:25 AM Rob Herring <robh@...nel.org> wrote:
> >
>
> Sorry for the late response...
>
> > On Tue, Aug 08, 2023 at 01:41:58AM +0800, Kyle Tso wrote:
> > > Define a new optional property "capabilities" which is a child node
> > > under connector to contain multiple USB Power Delivery capabilities.
> > >
> > > Define a new property with pattern (e.g. caps-0, caps-1) which is a
> >
> > A property in json-schema terms, but for DT it's a node not a property.
> > 'Define a child node ...' would be clearer.
> >
>
> Will do in the future patch
>
> > > child node under "capabilities". Each node contains PDO data of a
> > > selectable Power Delivery capability.
> > >
> > > Also define common properties for source-pdos, sink-pdos, and
> > > op-sink-microwatt that can be referenced.
> >
> > Why do we need this? What issue does this solve? The commit message
> > should answer those questions (always).
> >
>
> Will state the rationale in the future patch
>
> > > Signed-off-by: Kyle Tso <kyletso@...gle.com>
> > > ---
> > > v1 -> v2:
> > > - move source/sink-pdos to $defs and reference them in properties
> > >
> > >  .../bindings/connector/usb-connector.yaml     | 80 +++++++++++++------
> > >  1 file changed, 57 insertions(+), 23 deletions(-)
> > >
> > > diff --git a/Documentation/devicetree/bindings/connector/usb-connector.yaml b/Documentation/devicetree/bindings/connector/usb-connector.yaml
> > > index 1c4d3eb87763..c6b02dbda83f 100644
> > > --- a/Documentation/devicetree/bindings/connector/usb-connector.yaml
> > > +++ b/Documentation/devicetree/bindings/connector/usb-connector.yaml
> > > @@ -117,28 +117,10 @@ properties:
> > >    # The following are optional properties for "usb-c-connector" with power
> > >    # delivery support.
> > >    source-pdos:
> > > -    description: An array of u32 with each entry providing supported power
> > > -      source data object(PDO), the detailed bit definitions of PDO can be found
> > > -      in "Universal Serial Bus Power Delivery Specification" chapter 6.4.1.2
> > > -      Source_Capabilities Message, the order of each entry(PDO) should follow
> > > -      the PD spec chapter 6.4.1. Required for power source and power dual role.
> > > -      User can specify the source PDO array via PDO_FIXED/BATT/VAR/PPS_APDO()
> > > -      defined in dt-bindings/usb/pd.h.
> > > -    minItems: 1
> > > -    maxItems: 7
> > > -    $ref: /schemas/types.yaml#/definitions/uint32-array
> > > +    $ref: "#/$defs/source-pdos"
> > >
> > >    sink-pdos:
> > > -    description: An array of u32 with each entry providing supported power sink
> > > -      data object(PDO), the detailed bit definitions of PDO can be found in
> > > -      "Universal Serial Bus Power Delivery Specification" chapter 6.4.1.3
> > > -      Sink Capabilities Message, the order of each entry(PDO) should follow the
> > > -      PD spec chapter 6.4.1. Required for power sink and power dual role. User
> > > -      can specify the sink PDO array via PDO_FIXED/BATT/VAR/PPS_APDO() defined
> > > -      in dt-bindings/usb/pd.h.
> > > -    minItems: 1
> > > -    maxItems: 7
> > > -    $ref: /schemas/types.yaml#/definitions/uint32-array
> > > +    $ref: "#/$defs/sink-pdos"
> > >
> > >    sink-vdos:
> > >      description: An array of u32 with each entry, a Vendor Defined Message Object (VDO),
> > > @@ -164,9 +146,7 @@ properties:
> > >      $ref: /schemas/types.yaml#/definitions/uint32-array
> > >
> > >    op-sink-microwatt:
> > > -    description: Sink required operating power in microwatt, if source can't
> > > -      offer the power, Capability Mismatch is set. Required for power sink and
> > > -      power dual role.
> > > +    $ref: "#/$defs/op-sink-microwatt"
> > >
> > >    port:
> > >      $ref: /schemas/graph.yaml#/properties/port
> > > @@ -228,6 +208,30 @@ properties:
> > >        SNK_READY for non-pd link.
> > >      type: boolean
> > >
> > > +  capabilities:
> > > +    description: A child node to contain all the selectable USB Power Delivery capabilities.
> > > +    type: object
> > > +
> > > +    patternProperties:
> > > +      "^caps-[0-9]+$":
> > > +        description: Child nodes under "capabilities" node. Each node contains a selectable USB
> > > +          Power Delivery capability.
> > > +        type: object
> > > +
> > > +        properties:
> > > +          source-pdos:
> > > +            $ref: "#/$defs/source-pdos"
> > > +
> > > +          sink-pdos:
> > > +            $ref: "#/$defs/sink-pdos"
> > > +
> > > +          op-sink-microwatt:
> > > +            $ref: "#/$defs/op-sink-microwatt"
> > > +
> > > +        additionalProperties: false
> > > +
> > > +    additionalProperties: false
> > > +
> > >  dependencies:
> > >    sink-vdos-v1: [ 'sink-vdos' ]
> > >    sink-vdos: [ 'sink-vdos-v1' ]
> > > @@ -235,6 +239,36 @@ dependencies:
> > >  required:
> > >    - compatible
> > >
> > > +$defs:
> >
> > Make this:
> >
> > $defs:
> >   capabilities:
> >     properties:
> >       ...
> >
> > And then just reference "#/$defs/capabilities" at the top-level and in
> > caps-[0-9] node schema.
> >
> > You'll need to use unevaluatedProperties instead of additionalProperties
> > as well.
> >
>
> I am sorry I don't understand this part. Could you explain more?
>
> In $defs, define a whole structure of "capabilities" which has
> patternProperties "caps-[0-9]+", and inside "caps-[0-9]+" there are
> properties "source/sink-pdos" ?

No, define a list of properties under a def. Here's a more complete example:

$defs:
  capabilities:
    properties:
      source-pdos:
        ...

      sink-pdos:
        ...

And then add "$ref: '#/$defs/capabilities'" at the top-level of this
schema doc and under "caps-[0-9]+":

    patternProperties:
      "^caps-[0-9]+$":
        description: Child nodes under "capabilities" node. Each node
contains a selectable USB
          Power Delivery capability.
        type: object
        $ref: "#/$defs/capabilities"
        unevaluatedProperties: false

unevaluatedProperties is needed because it can "see" properties
defined in a $ref to get the full list of properties for a node.

Rob