Re: [net-next v4 1/3] dt-bindings: net: dsa: yt921x: Add Motorcomm YT921x switch support

[Krzysztof Kozlowski <krzk@kernel.org>]

On 18/08/2025 18:55, Andrew Lunn wrote:
>> +  motorcomm,switch-id:
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    description: |
>> +      Value selected by Pin SWITCH_ID_1 / SWITCH_ID_0.
>> +
>> +      Up to 4 chips can share the same MII port ('reg' in DT) by giving
>> +      different SWITCH_ID values. The default value should work if only one chip
>> +      is present.
>> +    enum: [0, 1, 2, 3]
>> +    default: 0
> 
> It is like getting blood from a stone.
> 
> So what you are saying is that you have:
> 
>     mdio {
>         #address-cells = <1>;
>         #size-cells = <0>;
> 
>         switch@1d {
>             compatible = "motorcomm,yt9215";
>             /* default 0x1d, alternate 0x0 */
>             reg = <0x1d>;
>             motorcomm,switch-id = <0>;
>             reset-gpios = <&tlmm 39 GPIO_ACTIVE_LOW>;
> ...
> 	}
> 
>         switch@1d {
>             compatible = "motorcomm,yt9215";
>             reg = <0x1d>;
>             motorcomm,switch-id = <1>;
>             reset-gpios = <&tlmm 39 GPIO_ACTIVE_LOW>;
> ...
> 	}
> 
>         switch@1d {
>             compatible = "motorcomm,yt9215";
>             reg = <0x1d>;
>             motorcomm,switch-id = <2>;
>             reset-gpios = <&tlmm 39 GPIO_ACTIVE_LOW>;
> ...
> 	}
>     }
> 
> Have you tested this? My _guess_ is, it does not work.

Regardless if kernel actually works with this, but duplicating unit
address is not supported, so this obviously would be wrong. I guess
that's the answer for switch-id.

Best regards,
Krzysztof