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.

Reviewed-by: Christopher Obbard <christopher.obbard@linaro.org>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@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 5442f981baebc..94a29f439ccf4 100644
--- a/Documentation/devicetree/bindings/media/qcom,x1e80100-camss.yaml
+++ b/Documentation/devicetree/bindings/media/qcom,x1e80100-camss.yaml
@@ -152,7 +152,8 @@ 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]$":
@@ -160,26 +161,86 @@ 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
+
 patternProperties:
   "^phy@[0-9a-f]+$":
     $ref: /schemas/phy/qcom,x1e80100-csi2-phy.yaml

-- 
2.52.0