Re: [PATCH/RFC 2/6] dt-bindings: display: bridge: renesas,dw-hdmi: Convert binding to YAML

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hallo again,

On Mon, Apr 06, 2020 at 02:28:57PM +0300, Laurent Pinchart wrote:
> On Mon, Apr 06, 2020 at 09:57:05AM +0200, Maxime Ripard wrote:
> > On Mon, Apr 06, 2020 at 02:39:31AM +0300, Laurent Pinchart wrote:
> > > diff --git a/Documentation/devicetree/bindings/display/bridge/renesas,dw-hdmi.yaml b/Documentation/devicetree/bindings/display/bridge/renesas,dw-hdmi.yaml
> > > new file mode 100644
> > > index 000000000000..9a543740c81d
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/display/bridge/renesas,dw-hdmi.yaml
> > > @@ -0,0 +1,142 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/display/bridge/renesas,dw-hdmi.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Renesas R-Car DWC HDMI TX Encoder
> > > +
> > > +maintainers:
> > > +  - Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> > > +
> > > +description: |
> > > +  The HDMI transmitter is a Synopsys DesignWare HDMI 1.4 TX controller IP
> > > +  with a companion PHY IP.
> > > +
> > > +allOf:
> > > +  - $ref: synopsys,dw-hdmi.yaml#
> > > +
> > > +properties:
> > > +  compatible:
> > > +    items:
> > > +      - enum:
> > > +        - renesas,r8a774a1-hdmi # for R8A774A1 (RZ/G2M) compatible HDMI TX
> > > +        - renesas,r8a774b1-hdmi # for R8A774B1 (RZ/G2N) compatible HDMI TX
> > > +        - renesas,r8a7795-hdmi # for R8A7795 (R-Car H3) compatible HDMI TX
> > > +        - renesas,r8a7796-hdmi # for R8A7796 (R-Car M3-W) compatible HDMI TX
> > > +        - renesas,r8a77965-hdmi # for R8A77965 (R-Car M3-N) compatible HDMI TX
> > > +      - const: renesas,rcar-gen3-hdmi
> > > +
> > > +  reg: true
> > > +
> > > +  reg-io-width:
> > > +    const: 1
> > > +
> > > +  clocks:
> > > +    minItems: 2
> > > +    maxItems: 2
> > 
> > You don't need both, if one is missing the other will be filled by the
> > dt-schema tools. In this particular case, I guess maxItems would make
> > more sense.
> 
> Fixed.
> 
> > > +
> > > +  clock-names:
> > > +    items:
> > > +      - const: iahb
> > > +      - const: isfr
> > > +
> > > +  interrupts: true
> > > +
> > > +  ports:
> > > +    type: object
> > > +    description: |
> > > +      This device has three video ports. Their connections are modelled using the
> > > +      OF graph bindings specified in Documentation/devicetree/bindings/graph.txt.
> > > +      Each port shall have a single endpoint.
> > > +
> > > +    properties:
> > > +      '#address-cells':
> > > +        const: 1
> > > +
> > > +      '#size-cells':
> > > +        const: 0
> > > +
> > > +      port@0:
> > > +        type: object
> > > +        description: Parallel RGB input port
> > > +
> > > +      port@1:
> > > +        type: object
> > > +        description: HDMI output port
> > > +
> > > +      port@2:
> > > +        type: object
> > > +        description: Sound input port
> > > +
> > > +    required:
> > > +      - port@0
> > > +      - port@1
> > > +      - port@2
> > > +
> > > +    additionalProperties: false

Would it also make sense to use unevaluatedProperties here, and drop
#address-cells and #size-cells above as they're already evaluated in
synopsys,dw-hdmi.yaml ?

> > > +
> > > +  power-domains:
> > > +    maxItems: 1
> > > +
> > > +required:
> > > +  - compatible
> > > +  - reg
> > > +  - clocks
> > > +  - clock-names
> > > +  - interrupts
> > > +  - ports
> > > +
> > > +additionalProperties: false
> > 
> > In the case where you have some kind of generic schema and then a more
> > specific one like you have here, unevaluatedProperties make more sense
> > that additionalProperties.
> > 
> > additionalProperties checks that there are no extra properties on the
> > current schema, which is a problem here since you have to duplicate
> > the entire list of properties found in the generic schema, while
> > unevaluatedProperties checks that there are no extra properties in the
> > entire set of all schemas that apply to this node.
> > 
> > This way, you can just put what is different from the generic schema,
> > and you don't have to keep it in sync.
> > 
> > It's a feature that has been added in the spec of the schemas that
> > went on right after the one we support in the tools, so for now the
> > kernel meta-schemas only allows that property to be there (just like
> > deprecated) but won't do anything.
> > 
> > This should be fixed quite soon however, the library we depend on
> > has started to work on that spec apparently.
> 
> Should I postpone this series until support for unevaluatedProperties is
> available, to be able to test this ?

Also, to make sure I understand this correctly, does it mean I can drop
"reg: true" and "interrupts: true" ?

-- 
Regards,

Laurent Pinchart
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