Re: [RFC PATCH net-next v2 1/2] dt-bindings: net: pse-pd: Add bindings for LTC4266 PSE Controller

[Kory Maincent <kory.maincent@bootlin.com>]

Hello Kyle,

Glad to see the v2 landing in the mailing list.

On 8/20/26 16:25, Kyle Swenson wrote:
> Add the LTC4266 Power Sourcing Equipment controller device tree bindings
> documentation.
> 
> Signed-off-by: Kyle Swenson <kyle.swenson@est.tech>
> ---
>   .../bindings/net/pse-pd/lltc,ltc4266.yaml     | 180 ++++++++++++++++++
>   1 file changed, 180 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/net/pse-pd/lltc,ltc4266.yaml
> 
> diff --git a/Documentation/devicetree/bindings/net/pse-pd/lltc,ltc4266.yaml b/Documentation/devicetree/bindings/net/pse-pd/lltc,ltc4266.yaml
> new file mode 100644
> index 000000000000..b3da8fea0b07
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/net/pse-pd/lltc,ltc4266.yaml
> @@ -0,0 +1,180 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/net/pse-pd/lltc,ltc4266.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Linear Technology LTC4266 Power Sourcing Equipment controller
> +
> +maintainers:
> +  - Kyle Swenson <kyle.swenson@est.tech>
> +
> +allOf:
> +  - $ref: pse-controller.yaml#
> +
> +properties:
> +  compatible:
> +    enum:
> +      - lltc,ltc4266
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  reset-gpios:
> +    maxItems: 1

The reset-gpios is currently not implemented in your driver. Maybe add 
it in the binding when it will be the case.

> +  channels:
> +    type: object
> +    additionalProperties: false
> +    description:
> +      Defines the 4 physical delivery channels on the controller that can be
> +      referenced by PSE PIs through their "pairsets" property. The actual port
> +      matrix mapping is created when PSE PIs reference these channels in their
> +      pairsets.
> +
> +    properties:
> +      '#address-cells':
> +        const: 1
> +
> +      '#size-cells':
> +        const: 0
> +
> +    patternProperties:
> +      '^channel@[0-3]$':
> +        type: object
> +        additionalProperties: false
> +
> +        properties:
> +          reg:
> +            maxItems: 1
> +
> +          sense-resistor-micro-ohms:
> +            description: Sense resistor connected to the channel's MOSFET, used
> +              for current measurement for overcurrent detection.
> +            enum: [250000, 500000]
> +
> +        required:
> +          - reg
> +          - sense-resistor-micro-ohms

I am bit skeptical about having sense-resistor-micro-ohms as a mandatory 
parameter. As you have described it's only for current measurement so 
it's not a requirement for PSE functioning. Maybe set it as a default 
value if not specified.

Else LGTM.

> +    required:
> +      - '#address-cells'
> +      - '#size-cells'
> +
> +  pse-pis:
> +    type: object
> +    additionalProperties: false
> +
> +    properties:
> +      '#address-cells':
> +        const: 1
> +
> +      '#size-cells':
> +        const: 0
> +
> +    patternProperties:
> +      '^pse-pi@[0-3]$':
> +        type: object
> +        properties:
> +          pairsets:
> +            description: The LTC4266 delivers power to a PI over a single
> +              pairset, driven by one of the controller's four channels. There
> +              is no 4-pair mode spreading a PI over two channels, so exactly
> +              one channel phandle is expected.
> +            maxItems: 1
> +          pairset-names:
> +            maxItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +  - channels
> +  - pse-pis
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +
> +    i2c {
> +      #address-cells = <1>;
> +      #size-cells = <0>;
> +
> +      ethernet-pse@2f {
> +        compatible = "lltc,ltc4266";
> +        reg = <0x2f>;
> +        interrupts = <8 IRQ_TYPE_LEVEL_LOW>;
> +        interrupt-parent = <&gpio>;
> +
> +        channels {
> +          #address-cells = <1>;
> +          #size-cells = <0>;
> +
> +          phys0: channel@0 {
> +            reg = <0>;
> +            sense-resistor-micro-ohms = <500000>;
> +          };
> +
> +          phys1: channel@1 {
> +            reg = <1>;
> +            sense-resistor-micro-ohms = <500000>;
> +          };
> +
> +          phys2: channel@2 {
> +            reg = <2>;
> +            sense-resistor-micro-ohms = <500000>;
> +          };
> +
> +          phys3: channel@3 {
> +            reg = <3>;
> +            sense-resistor-micro-ohms = <500000>;
> +          };
> +        };
> +
> +        pse-pis {
> +          #address-cells = <1>;
> +          #size-cells = <0>;
> +
> +          pse_pi0: pse-pi@0 {
> +            reg = <0>;
> +            #pse-cells = <0>;
> +            pairset-names = "alternative-a";
> +            pairsets = <&phys0>;
> +            polarity-supported = "MDI";
> +            vpwr-supply = <&vreg_pse>;
> +          };
> +
> +          pse_pi1: pse-pi@1 {
> +            reg = <1>;
> +            #pse-cells = <0>;
> +            pairset-names = "alternative-a";
> +            pairsets = <&phys1>;
> +            polarity-supported = "MDI";
> +            vpwr-supply = <&vreg_pse>;
> +          };
> +
> +          pse_pi2: pse-pi@2 {
> +            reg = <2>;
> +            #pse-cells = <0>;
> +            pairset-names = "alternative-a";
> +            pairsets = <&phys2>;
> +            polarity-supported = "MDI";
> +            vpwr-supply = <&vreg_pse>;
> +          };
> +
> +          pse_pi3: pse-pi@3 {
> +            reg = <3>;
> +            #pse-cells = <0>;
> +            pairset-names = "alternative-a";
> +            pairsets = <&phys3>;
> +            polarity-supported = "MDI";
> +            vpwr-supply = <&vreg_pse>;
> +          };
> +        };
> +      };
> +    };

-- 
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com