Re: [PATCH net-next v2 2/4] dt-bindings: net: dsa: Add SoC-e SWIP switch

[Vasilij Strassheim <v.strassheim@linutronix.de>]

On Mon, 2026-09-07 at 21:04 +0200, Andrew Lunn wrote:
> > +    patternProperties:
> > +      '^mdio@[0-9a-f]+$':
> > +        $ref: /schemas/net/mdio.yaml#
> > +        unevaluatedProperties: false
> > +
> > +        properties:
> > +          reg:
> > +            maximum: 30
> > +            description:
> > +              MDIO controller output index, which must be lower than the
> > +              number of implemented switch ports.
> 
> Is there a relationship between an MDIO bus and a port?

Yes, there is a one-to-one relationship for this IP. The MDIO bus
selector corresponds to the switch port index.

> 
> I'm just wondering if the MDIO bus should be a property of the
> port. There are switch which have an MDIO bus per port.
> 

I see this model in the new NETC switch binding. I will move the
optional mdio node below the corresponding ethernet-port@N and derive
the selector from the port's reg.

> > +patternProperties:
> > +  '^(ethernet-)?ports$':
> > +    patternProperties:
> > +      '^(ethernet-)?port@[0-9a-f]+$':
> > +        $ref: dsa-port.yaml#
> > +        unevaluatedProperties: false
> > +
> > +        properties:
> > +          reg:
> > +            maximum: 30
> > +            description:
> > +              Switch port index. Supported switch configurations have
> > +              up to 31 ports, numbered from 0 through 30.
> 
> 30 seems odd. Is 31 something special? 
> 

The hardware stores the port count directly in a 5-bit field, so 31 is
the maximum representable count. Therefore, valid zero-based port
indices range from 0 to 30. The switch documentation is unclear about
the encoding, but I tested a three-port configuration and the field
contained 3.

> > +examples:
> > +  - |
> > +    ethernet-switch@80020000 {
> > +        compatible = "soce,swip-00-04-0c-10";
> > +        reg = <0x80020000 0x10000>;
> > +
> > +        ports {
> > +            #address-cells = <1>;
> > +            #size-cells = <0>;
> > +
> > +            port@0 {
> > +                reg = <0>;
> > +                label = "lan0";
> 
> label is another thing in DSA which is today not best practice. I
> would drop this.

I have no problem removing the label from example. I'll have to
adjust it anyway for the new MDIO bus and port relationship.

> 
> 	Andrew

Thanks,
Vasilij