linux-kernel - Re: [PATCH v3 1/2] dt-bindings: connector: Add child nodes for multiple PD capabilities

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Date:   Tue, 14 Nov 2023 14:55:19 -0600
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 v3 1/2] dt-bindings: connector: Add child nodes for
 multiple PD capabilities

On Tue, Oct 31, 2023 at 01:13:47AM +0800, Kyle Tso wrote:
> Commit 662a60102c12 ("usb: typec: Separate USB Power Delivery from USB
> Type-C") allows userspace to configure the PD of a port by selecting
> different set of predefined PD capabilities. Define the PD capability
> sets in DT for better configurability in device modules.

What Linux userspace does is irrelevant to bindings. Explain this in 
terms of the h/w having multiple capabilities. I'm still not clear how 
this is tied to the h/w rather than just multiple configurations within 
the limits of what the h/w can support.

> 
> Define a child node "capabilities" to contain multiple USB Power
> Delivery capabilities.
> 
> Define a child node with pattern (e.g. caps-0, caps-1) 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.
> 
> Signed-off-by: Kyle Tso <kyletso@...gle.com>
> ---
> v2 -> v3
> - Updated the commit message
> - Remain unchanged for the comments about the property/node refactor
> 
> .../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 7c8a3e8430d3..d7ece063cb2c 100644
> --- a/Documentation/devicetree/bindings/connector/usb-connector.yaml
> +++ b/Documentation/devicetree/bindings/connector/usb-connector.yaml
> @@ -120,28 +120,10 @@ 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),
> @@ -167,9 +149,7 @@ 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:
>      $ref: /schemas/graph.yaml#/properties/port
> @@ -231,6 +211,30 @@ properties:
>        SNK_READY for non-pd link.
>      type: boolean
>  
> +  capabilities:
> +    description: A child node to contain all the selectable USB Power Delivery capabilities.
> +    type: object
> +
> +    patternProperties:
> +      "^caps-[0-9]+$":
> +        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 ]
> @@ -238,6 +242,36 @@ dependencies:
>  required:
>    - compatible
>  
> +$defs:
> +  source-pdos:

Rather than a bunch a $refs to per property definitions, define the 
collection of properties and then reference that collection:

$defs:
  capabilities:
    type: object

    properties:
      source-pdos: ...

And then at the node level, make the reference:

"^caps-[0-9]+$":
  $ref: "#/$defs/capabilities"
  unevaluatedProperties: false

Rob