Re: [PATCH v8 03/18] dt-bindings: media: qcom,x1e80100-camss: Add support for combo-mode endpoints

[Christopher Obbard <christopher.obbard@linaro.org>]

Hi Bryan,

On Wed, 2026-02-25 at 15:11 +0000, Bryan O'Donoghue wrote:
> Qualcomm CSI2 PHYs support a mode where two sensors may be attached to the
> one CSIPHY.
> 
> When we have one endpoint we may have
> - DPHY 1, 2 or 4 data lanes + 1 clock lane
> - CPHY 3 wire data lane
> 
> When we have two endpoints this indicates the special fixed combo-mode.
> - DPHY endpoint0 => 2+1 and endpoint1 => 1+1 data-lane/clock-lane combination.
> 
> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>

Reviewed-by: Christopher Obbard <christopher.obbard@linaro.org>

> ---
>  .../bindings/media/qcom,x1e80100-camss.yaml        | 69 ++++++++++++++++++++--
>  1 file changed, 65 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/media/qcom,x1e80100-camss.yaml b/Documentation/devicetree/bindings/media/qcom,x1e80100-camss.yaml
> index ff14a8248321e..462b1355c9fb7 100644
> --- a/Documentation/devicetree/bindings/media/qcom,x1e80100-camss.yaml
> +++ b/Documentation/devicetree/bindings/media/qcom,x1e80100-camss.yaml
> @@ -116,7 +116,8 @@ properties:
>      $ref: /schemas/graph.yaml#/properties/ports
>  
>      description:
> -      CSI input ports.
> +      CSI input ports. Supports either standard single sensor mode or
> +      Qualcomm's combo mode with one sensor in 2x1 + 1x1 data-lane, clock-lane mode.
>  
>      patternProperties:
>        "^port@[0-3]$":
> @@ -124,26 +125,86 @@ properties:
>          unevaluatedProperties: false
>  
>          description:
> -          Input port for receiving CSI data from a CSIPHY.
> +          Input port for receiving CSI data.
>  
>          properties:
> -          endpoint:
> +          endpoint@0:
>              $ref: video-interfaces.yaml#
>              unevaluatedProperties: false
>  
> +            description:
> +              Endpoint for receiving a single sensor input (or first leg of combo).
> +
>              properties:
>                data-lanes:
>                  minItems: 1
> -                maxItems: 4
> +                maxItems: 4 # Base max allows 4 (for D-PHY)
> +
> +              clock-lanes:
> +                maxItems: 1
>  
>                bus-type:
>                  enum:
>                    - 1 # MEDIA_BUS_TYPE_CSI2_CPHY
>                    - 4 # MEDIA_BUS_TYPE_CSI2_DPHY
>  
> +          endpoint@1:
> +            $ref: video-interfaces.yaml#
> +            unevaluatedProperties: false
> +
> +            description:
> +              Endpoint for receiving the second leg of a combo sensor input.
> +
> +            properties:
> +              data-lanes:
> +                maxItems: 1
> +
> +              clock-lanes:
> +                maxItems: 1
> +
> +              bus-type:
> +                const: 4 # Combo is D-PHY specific
> +
>              required:
>                - data-lanes
>  
> +        allOf:
> +          # Case 1: Combo Mode (endpoint@1 is present)
> +          # If endpoint@1 exists, we restrict endpoint@0 to 2 lanes (D-PHY split)
> +          - if:
> +              required:
> +                - endpoint@1
> +            then:
> +              properties:
> +                endpoint@0:
> +                  properties:
> +                    data-lanes:
> +                      minItems: 2
> +                      maxItems: 2
> +                    bus-type:
> +                      const: 4
> +                endpoint@1:
> +                  properties:
> +                    data-lanes:
> +                      minItems: 1
> +                      maxItems: 1
> +                    bus-type:
> +                      const: 4
> +
> +          # Case 2: Single Mode (endpoint@1 is missing)
> +          # We explicitly allow up to 4 lanes here to cover the D-PHY use case.
> +          - if:
> +              not:
> +                required:
> +                  - endpoint@1
> +            then:
> +              properties:
> +                endpoint@0:
> +                  properties:
> +                    data-lanes:
> +                      minItems: 1
> +                      maxItems: 4
> +
>  required:
>    - compatible
>    - reg