Re: [net-next v5 1/6] dt-bindings: net: Add MTIP L2 switch description

[Lukasz Majewski <lukma@denx.de>]

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Hi Rob,

> On Mon, Apr 14, 2025 at 04:01:23PM +0200, Lukasz Majewski wrote:
> > This patch provides description of the MTIP L2 switch available in
> > some NXP's SOCs - e.g. imx287.
> > 
> > Signed-off-by: Lukasz Majewski <lukma@denx.de>
> > ---
> > Changes for v2:
> > - Rename the file to match exactly the compatible
> >   (nxp,imx287-mtip-switch)
> > 
> > Changes for v3:
> > - Remove '-' from const:'nxp,imx287-mtip-switch'
> > - Use '^port@[12]+$' for port patternProperties
> > - Drop status = "okay";
> > - Provide proper indentation for 'example' binding (replace 8
> >   spaces with 4 spaces)
> > - Remove smsc,disable-energy-detect; property
> > - Remove interrupt-parent and interrupts properties as not required
> > - Remove #address-cells and #size-cells from required properties
> > check
> > - remove description from reg:
> > - Add $ref: ethernet-switch.yaml#
> > 
> > Changes for v4:
> > - Use $ref: ethernet-switch.yaml#/$defs/ethernet-ports and remove
> > already referenced properties
> > - Rename file to nxp,imx28-mtip-switch.yaml
> > 
> > Changes for v5:
> > - Provide proper description for 'ethernet-port' node
> > ---
> >  .../bindings/net/nxp,imx28-mtip-switch.yaml   | 141
> > ++++++++++++++++++ 1 file changed, 141 insertions(+)
> >  create mode 100644
> > Documentation/devicetree/bindings/net/nxp,imx28-mtip-switch.yaml
> > 
> > diff --git
> > a/Documentation/devicetree/bindings/net/nxp,imx28-mtip-switch.yaml
> > b/Documentation/devicetree/bindings/net/nxp,imx28-mtip-switch.yaml
> > new file mode 100644 index 000000000000..6f2b5a277ac2 --- /dev/null
> > +++
> > b/Documentation/devicetree/bindings/net/nxp,imx28-mtip-switch.yaml
> > @@ -0,0 +1,141 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR
> > BSD-2-Clause) +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/net/nxp,imx28-mtip-switch.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: NXP SoC Ethernet Switch Controller (L2 MoreThanIP switch)
> > +
> > +maintainers:
> > +  - Lukasz Majewski <lukma@denx.de>
> > +
> > +description:
> > +  The 2-port switch ethernet subsystem provides ethernet packet
> > (L2)
> > +  communication and can be configured as an ethernet switch. It
> > provides the
> > +  reduced media independent interface (RMII), the management data
> > input
> > +  output (MDIO) for physical layer device (PHY) management.
> > +
> > +$ref: ethernet-switch.yaml#/$defs/ethernet-ports
> > +
> > +properties:
> > +  compatible:
> > +    const: nxp,imx28-mtip-switch
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  phy-supply:
> > +    description:
> > +      Regulator that powers Ethernet PHYs.
> > +
> > +  clocks:
> > +    items:
> > +      - description: Register accessing clock
> > +      - description: Bus access clock
> > +      - description: Output clock for external device - e.g. PHY
> > source clock
> > +      - description: IEEE1588 timer clock
> > +
> > +  clock-names:
> > +    items:
> > +      - const: ipg
> > +      - const: ahb
> > +      - const: enet_out
> > +      - const: ptp
> > +
> > +  interrupts:
> > +    items:
> > +      - description: Switch interrupt
> > +      - description: ENET0 interrupt
> > +      - description: ENET1 interrupt
> > +
> > +  pinctrl-names: true
> > +
> > +  ethernet-ports:
> > +    type: object
> > +    additionalProperties: true
> > +    properties:
> > +      ethernet-port:
> > +        type: object
> > +        unevaluatedProperties: false  
> 
> This is going to fail if you have any property other than 'reg'.

The DT schema check shall fail when reg is not equal to 1 or 2, as this
switch has only two ports.

> But 
> then it will never be applied because you never have a node called
> 'ethernet-port' since you have more than 1 child node.
> You need this 
> under 'patternProperties' and 'additionalProperties: true' instead.
> And please test some of the requirements here. Like a reg value of 3
> or remove 'phy-mode'.

In linux-next we now also have realtek,rtl9301-switch.yaml which uses
just:

properties:
  ethernet-ports:
    type: object

but when in "examples" I do remove for example "phy-handle" the command:
make dt_binding_check DT_SCHEMA_FILES=realtek,rtl9301-switch.yaml

is executed without errors.


IMHO the problem is with proper usage of
$ref: ethernet-switch.yaml#/$defs/ethernet-ports

which shall in my case be extended to have:
$ref: ethernet-switch.yaml#/$defs/ethernet-ports/patternProperties

In the case of MTIP - the following SCHEMA description shall be used:

  ethernet-ports:
    type: object
    $ref: ethernet-switch.yaml#/$defs/ethernet-ports/patternProperties
    additionalProperties: true

    patternProperties:
      '^ethernet-port@[12]$':
        type: object
        additionalProperties: true
        properties:
          reg:
            items:
              - enum: [1, 2]
            description: MTIP L2 switch port number

        required:
          - reg
          - label
          - phy-mode
          - phy-handle


And then, when I remove from 'example:' the 'label':

make dt_binding_check DT_SCHEMA_FILES=nxp,imx28-mtip-switch.yaml
/Documentation/devicetree/bindings/net/nxp,imx28-mtip-switch.example.dtb:
switch@800f0000: ethernet-ports:ethernet-port@2: 'label' is a required
property from schema $id:
http://devicetree.org/schemas/net/nxp,imx28-mtip-switch.yaml#
/Documentation/devicetree/bindings/net/nxp,imx28-mtip-switch.example.dtb:
switch@800f0000: Unevaluated properties are not allowed
('ethernet-ports' was unexpected) from schema $id:
http://devicetree.org/schemas/net/nxp,imx28-mtip-switch.yaml#

or when reg = <3>;

Documentation/devicetree/bindings/net/nxp,imx28-mtip-switch.example.dtb:
switch@800f0000: ethernet-ports:ethernet-port@2:reg:0:0: 3 is not one
of [1, 2]

When I do use the untouched example: node - it compiles without errors.

I do guess that this is the expected behaviour... :-)

> 
> > +
> > +        properties:
> > +          reg:
> > +            items:
> > +              - enum: [1, 2]
> > +            description: MTIP L2 switch port number
> > +
> > +        required:
> > +          - reg
> > +          - label
> > +          - phy-mode
> > +          - phy-handle  




Best regards,

Lukasz Majewski

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