Re: [PATCH v4 1/9] dt-bindings: soc: qcom: eud: Add per-path child nodes for UTMI routing

[Dmitry Baryshkov]

On Fri, May 01, 2026 at 10:06:27AM -0700, Elson Serrao wrote:
> The Qualcomm Embedded USB Debugger (EUD) can intercept one or two
> independent High-Speed UTMI paths, depending on the SoC configuration.
> Each path is distinct, with its own connector/controller connection
> and role-dependent UTMI routing.
> 
> Because the EUD sits between the USB connector and the USB controller,
> it must relay role changes across the UTMI path. In device role, the
> EUD inserts its internal hub into the path to enable debug
> functionality. In host role, the path remains directly connected
> between the PHY and the USB controller, bypassing the EUD hub. These
> hardware constraints require per-path role awareness, as UTMI path
> roles may differ.
> 
> The existing binding models only a single UTMI path and assumes a
> uniform routing model. While sufficient for simple device-role-only
> configurations, this representation does not accurately describe EUD
> hardware when role switching and/or multiple UTMI paths are involved.
> 
> To address this limitation, per-path child nodes are introduced to
> describe individual UTMI paths through the EUD. Each path includes its
> own ports description, allowing controller and connector associations,
> as well as role-aware routing.
> 
> Signed-off-by: Elson Serrao <elson.serrao@xxxxxxxxxxxxxxxx>
> ---
>  .../bindings/soc/qcom/qcom,eud.yaml           | 55 ++++++++++++++++++-
>  1 file changed, 54 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,eud.yaml b/Documentation/devicetree/bindings/soc/qcom/qcom,eud.yaml
> index 84218636c0d8..21f75038a81c 100644
> --- a/Documentation/devicetree/bindings/soc/qcom/qcom,eud.yaml
> +++ b/Documentation/devicetree/bindings/soc/qcom/qcom,eud.yaml
> @@ -45,10 +45,63 @@ properties:
>          $ref: /schemas/graph.yaml#/properties/port
>          description: This port is to be attached to the type C connector.
>  
> +  '#address-cells':
> +    const: 1
> +
> +  '#size-cells':
> +    const: 0
> +
> +patternProperties:
> +  "^eud-path@[0-1]$":
> +    type: object
> +    description:
> +      Represents one High-Speed UTMI path that EUD intercepts. Use eud-path nodes
> +      to associate role-switching behavior with specific port connections, allowing
> +      EUD to manage role transitions independently for each UTMI path.
> +
> +    properties:
> +      reg:
> +        maxItems: 1
> +        description: Path number
> +
> +      usb-role-switch:
> +        type: boolean
> +        description:
> +          Indicates that EUD should act as a role switch for this path.
> +          In device role, debug mode inserts the EUD hub into the UTMI path. In
> +          host role, the EUD hub is bypassed and UTMI traffic flows directly
> +          between the PHY and the USB controller.
> +
> +      ports:
> +        $ref: /schemas/graph.yaml#/properties/ports
> +        description:
> +          These ports are to be attached to the endpoint of the USB controller node
> +          and USB connector node.
> +
> +        properties:
> +          port@0:
> +            $ref: /schemas/graph.yaml#/properties/port
> +            description: This port is to be attached to the USB controller.
> +
> +          port@1:
> +            $ref: /schemas/graph.yaml#/properties/port
> +            description: This port is to be attached to the USB connector.
> +
> +    required:
> +      - reg
> +      - ports
> +
> +    additionalProperties: false
> +
>  required:
>    - compatible
>    - reg
> -  - ports
> +
> +oneOf:
> +  - required:
> +      - ports
> +  - required:
> +      - eud-path@0

Do we really need a separate eud-path node? It doesn't represent any
particular part of the EUD device. Can we simply add more ports to the
ports list?

For example:

ports {
	port@0 { endpoint { remote-endpoint = <&usb0_host>; }; };
	port@1 { endpoint { remote-endpoint = <&connector0; }; };
	port@2 { endpoint { remote-endpoint = <&usb1_host>; }; };
	port@3 { endpoint { remote-endpoint = <&connector1; }; };
};


-- 
With best wishes
Dmitry