Re: [PATCH v5 1/7] dt-bindings: display: verisilicon,dc: generalize for single-output variants

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

在 2026-06-25四的 17:33 +0100，Conor Dooley写道：
> On Thu, Jun 25, 2026 at 05:44:43PM +0800, Joey Lu wrote:
> > The verisilicon,dc binding was originally written for the T-Head
> > TH1520
> > SoC carrying a DC8200, and hard-codes five clocks, three resets and
> > two
> > output ports.
> > 
> > Add the Nuvoton MA35D1 DCUltraLite (nuvoton,ma35d1-dcu) to the
> > binding.
> > The DCUltraLite uses only two clocks (core, pix0) and one reset
> > (core),
> > with a single output port.
> > 
> > Use allOf/if blocks to express per-variant constraints rather than
> > hard-coding the DC8200 topology at the top level.  Each
> > compatible's
> > block constrains the clock and reset item counts; the nuvoton block
> > additionally overrides clock-names to the two names it actually
> > uses.
> > 
> > Signed-off-by: Joey Lu <a0987203069@gmail.com>
> > ---
> >  .../bindings/display/verisilicon,dc.yaml      | 57
> > +++++++++++++++++++
> >  1 file changed, 57 insertions(+)
> > 
> > diff --git
> > a/Documentation/devicetree/bindings/display/verisilicon,dc.yaml
> > b/Documentation/devicetree/bindings/display/verisilicon,dc.yaml
> > index 9dc35ab973f2..1e751f3c7ce8 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:
> > @@ -77,6 +78,62 @@ required:
> >    - clock-names
> >    - ports
> >  
> > +allOf:
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          contains:
> > +            const: thead,th1520-dc8200
> > +    then:
> > +      properties:
> > +        clocks:
> > +          minItems: 5
> > +          maxItems: 5
> > +
> > +        clock-names:
> > +          minItems: 5
> > +          maxItems: 5
> 
> All the maxItems here repeat the maximum constraint and do nothing.
> 
> Since you didn't change the minimum constraint at the top level, your
> minItems also do nothing.
> 
> > +
> > +        resets:
> > +          minItems: 3
> > +          maxItems: 3
> > +
> > +        reset-names:
> > +          minItems: 3
> > +          maxItems: 3
> > +
> > +      required:
> > +        - resets
> > +        - reset-names
> 
> Both conditional sections have this, but the original binding doesn't
> require these for the thead device. This is a functional change
> therefore and shouldn't be in a patch calling itself "generalise for
> single ended variants".

Well yes they're required.

Should I send a patch adding the `thead,th1520-dc8200` part of the
schema?

> 
> FWIW, adding your new compatible shouldn't really be in a patch with
> that subject either, it really should say "add support for nuvoton
> ma35d1" or something.
> 
> > +
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          contains:
> > +            const: nuvoton,ma35d1-dcu
> > +    then:
> > +      properties:
> > +        clocks:
> > +          minItems: 2
> 
> Anything that updates the minimum constraint should be done at the
> top
> level of this schema. The conditional section should then tighten the
> constraint, in this case that means only having maxItems.
> 
> > +          maxItems: 2
> > +
> > +        clock-names:
> > +          items:
> > +            - const: core
> > +            - const: pix0
> 
> Does this even work when the top level schema thinks clock 2 should
> be
> called axi?
> 
> > +
> > +        resets:
> > +          minItems: 1
> > +          maxItems: 1
> > +
> > +        reset-names:
> > +          items:
> > +            - const: core
> 
> This is just maxItems: 1.

Well the implicit rules of DT binding schemas are quite weird...

Thanks,
Icenowy

> 
> pw-bot: changes-requested
> 
> Thanks,
> Conor.
> 
> > +
> > +      required:
> > +        - resets
> > +        - reset-names
> > +
> >  additionalProperties: false
> >  
> >  examples:
> > -- 
> > 2.43.0
> >