Re: [PATCH v6 1/6] dt-bindings: display: verisilicon,dc: add support for nuvoton,ma35d1-dcu

[Joey Lu]

Icenowy Zheng 於 2026/9/9 下午 01:44 寫道:
> 在 2026-09-08二的 17:28 +0800，Joey Lu写道：
> > Add the Nuvoton MA35D1 DCUltraLite (nuvoton,ma35d1-dcu) to the
> > binding.
> > The DCUltraLite uses only four clocks (core, axi, ahb, pix0) and one
> > reset (core), with a single output port.
> >
> > The MA35D1 clock controller gates the core, AXI and AHB clocks with a
> > single bit, but each remains a distinct clock line feeding the IP
> > with
> > its own rate constraints, so all four must still be listed
> > individually
> > in the devicetree; core, axi and ahb happen to share the same clock
> > phandle.
> This is weird, but I must admit that we're limited by the Common Clock
> Framework here, so I cannot give a better solution either.
>
> Anyway let's settle with the current result.
>
> > Move the clocks/clock-names minItems to 4 and resets/reset-names
> > minItems to 1 at the top level, since that is the lowest count any
> > supported variant needs.  Add an allOf/if block that tightens the
> > constraint back up to the fixed 5-clock/3-reset topology required by
> > the existing thead,th1520-dc8200 compatible, and another one that
> > caps
> > the new nuvoton,ma35d1-dcu compatible at the 4-clock/1-reset count it
> > actually wires up.
> >
> > Signed-off-by: Joey Lu <a0987203069@xxxxxxxxx>
> > ---
> >   .../bindings/display/verisilicon,dc.yaml      | 44
> > +++++++++++++++++++
> >   1 file changed, 44 insertions(+)
> >
> > diff --git
> > a/Documentation/devicetree/bindings/display/verisilicon,dc.yaml
> > b/Documentation/devicetree/bindings/display/verisilicon,dc.yaml
> > index 919a900122012..773966677d0f4 100644
> > --- a/Documentation/devicetree/bindings/display/verisilicon,dc.yaml
> > +++ b/Documentation/devicetree/bindings/display/verisilicon,dc.yaml
> > @@ -17,6 +17,7 @@ properties:
> >       items:
> >         - enum:
> >             - thead,th1520-dc8200
> > +          - nuvoton,ma35d1-dcu
> >         - const: verisilicon,dc # DC IPs have discoverable ID/revision
> > registers
> >   
> >     reg:
> > @@ -26,6 +27,7 @@ properties:
> >       maxItems: 1
> >   
> >     clocks:
> > +    minItems: 4
> >       items:
> >         - description: DC Core clock
> >         - description: DMA AXI bus clock
> > @@ -34,6 +36,7 @@ properties:
> >         - description: Pixel clock of output 1
> >   
> >     clock-names:
> > +    minItems: 4
> >       items:
> >         - const: core
> >         - const: axi
> > @@ -42,12 +45,14 @@ properties:
> >         - const: pix1
> >   
> >     resets:
> > +    minItems: 1
> >       items:
> >         - description: DC Core reset
> >         - description: DMA AXI bus reset
> >         - description: Configuration AHB bus reset
> >   
> >     reset-names:
> > +    minItems: 1
> >       items:
> >         - const: core
> >         - const: axi
> > @@ -79,6 +84,45 @@ required:
> >     - reset-names
> >     - ports
> >   
> > +allOf:
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          contains:
> > +            const: thead,th1520-dc8200
> > +    then:
> > +      properties:
> > +        clocks:
> > +          minItems: 5
> > +
> > +        clock-names:
> > +          minItems: 5
> > +
> > +        resets:
> > +          minItems: 3
> > +
> > +        reset-names:
> > +          minItems: 3
> > +
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          contains:
> > +            const: nuvoton,ma35d1-dcu
> > +    then:
> > +      properties:
> > +        clocks:
> > +          maxItems: 4
> > +
> > +        clock-names:
> > +          maxItems: 4
> > +
> > +        resets:
> > +          maxItems: 1
> > +
> > +        reset-names:
> > +          maxItems: 1
> Maybe it's reasonable to restrict max port count to 1 for MA35D1?
> Although I am not sure about how to do this...
>
> Thanks,
> Icenowy
 I found the same kind of per-compatible port restriction already used 
upstream in renesas,du.yaml, e.g.:

        ports:
          properties:
            port@2: false
            port@3: false
          required:
            - port@0
            - port@1

Applied to our binding, that would look like:

        ports:
          properties:
            port@1: false
          required:
            - port@0

in the existing nuvoton,ma35d1-dcu allOf/if/then block, so schema checks 
would reject a port@1 node on this compatible instead of silently 
accepting it.

Happy to add it if you'd like the schema to enforce this, but wanted to 
check whether you consider it worth the extra lines given it doesn't 
reflect an actual bug in any DT today. Let me know which way you'd 
prefer and I'll fold it into the next version.

Thanks.
> > +
> >   additionalProperties: false
> >   
> >   examples: