Re: [PATCH 3/5] dt-bindings: display: simple-bridge: Document DPI color encoder

[Maxime Ripard <mripard@kernel.org>]

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On Tue, Mar 04, 2025 at 06:15:28PM +0800, Liu Ying wrote:
> A DPI color encoder, as a simple display bridge, converts input DPI color
> coding to output DPI color coding, like Adafruit Kippah DPI hat[1] which
> converts input 18-bit pixel data to 24-bit pixel data(with 2 low padding
> bits in every color component though). Document the DPI color encoder.
> 
> [1] https://learn.adafruit.com/adafruit-dpi-display-kippah-ttl-tft/downloads
> 
> Signed-off-by: Liu Ying <victor.liu@nxp.com>

So it's just a bunch of signals that aren't wired / set to the ground? I
assume to free a few GPIOs?

I guess that makes sense.

> ---
>  .../display/bridge/simple-bridge.yaml         | 89 ++++++++++++++++++-
>  1 file changed, 87 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/display/bridge/simple-bridge.yaml b/Documentation/devicetree/bindings/display/bridge/simple-bridge.yaml
> index 43cf4df9811a..c1747c033040 100644
> --- a/Documentation/devicetree/bindings/display/bridge/simple-bridge.yaml
> +++ b/Documentation/devicetree/bindings/display/bridge/simple-bridge.yaml
> @@ -27,6 +27,7 @@ properties:
>            - const: adi,adv7123
>        - enum:
>            - adi,adv7123
> +          - dpi-color-encoder

I don't think we can claim that there's a generic DPI color encoder.
Maybe we can add the prefix dumb or transparent?

>            - dumb-vga-dac
>            - ti,opa362
>            - ti,ths8134
> @@ -37,13 +38,31 @@ properties:
>  
>      properties:
>        port@0:
> -        $ref: /schemas/graph.yaml#/properties/port
> +        $ref: /schemas/graph.yaml#/$defs/port-base
> +        unevaluatedProperties: false
>          description: The bridge input
>  
> +        properties:
> +          endpoint:
> +            $ref: /schemas/media/video-interfaces.yaml#
> +            unevaluatedProperties: false
> +
> +            properties:
> +              dpi-color-coding: true
> +
>        port@1:
> -        $ref: /schemas/graph.yaml#/properties/port
> +        $ref: /schemas/graph.yaml#/$defs/port-base
> +        unevaluatedProperties: false
>          description: The bridge output
>  
> +        properties:
> +          endpoint:
> +            $ref: /schemas/media/video-interfaces.yaml#
> +            unevaluatedProperties: false
> +
> +            properties:
> +              dpi-color-coding: true
> +
>      required:
>        - port@0
>        - port@1
> @@ -61,6 +80,44 @@ required:
>  
>  additionalProperties: false
>  
> +allOf:
> +  - $ref: /schemas/display/dpi-color-coding.yaml#
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: dpi-color-encoder
> +    then:
> +      properties:
> +        ports:
> +          properties:
> +            port@0:
> +              properties:
> +                endpoint:
> +                  required:
> +                    - dpi-color-coding
> +
> +            port@1:
> +              properties:
> +                endpoint:
> +                  required:
> +                    - dpi-color-coding
> +    else:
> +      properties:
> +        ports:
> +          properties:
> +            port@0:
> +              properties:
> +                endpoint:
> +                  properties:
> +                    dpi-color-coding: false
> +
> +            port@1:
> +              properties:
> +                endpoint:
> +                  properties:
> +                    dpi-color-coding: false
> +

Also it complicates the binding enough to warrant for another binding for
that specific "component".

>  examples:
>    - |
>      bridge {
> @@ -88,4 +145,32 @@ examples:
>          };
>      };
>  
> +  - |
> +    bridge {
> +        compatible = "dpi-color-enoder";

You have a typo in the compatible.

Maxime

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