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

[Icenowy Zheng <zhengxingda@iscas.ac.cn>]

在 2026-09-10四的 09:52 +0800，Joey Lu写道：
> 
> 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@gmail.com>
> > > ---
> > >   .../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.

Personally I think this is good, but maybe adding it as an additional
patch after merging isn't a big problem, because this just plays as
kind of a safety guard.

Well this depends on how DT binding maintainers think, but as Conor has
dropped his Ack, this shouldn't be a big issue.

Thanks,
Icenowy

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