[PATCH v2 1/4] dt-bindings: display: verisilicon,dc: generalize for single-output variants

[Joey Lu]

The existing schema assumes a fixed clock/reset topology and dual-output
port structure matching the DC8200 IP block.  This prevents reuse for
single-output variants such as the Verisilicon DCU Lite used in the
Nuvoton MA35D1 SoC.

Rework the schema so that variant-specific constraints are expressed
via allOf/if-then-else:

- The thead,th1520-dc8200 compatible keeps its existing five-clock,
  three-reset, dual-port requirements.

- A standalone verisilicon,dc compatible covers IPs whose identity is
  discovered entirely through hardware registers; these have flexible
  clock and reset counts, a single 'port' property, and no 'ports'
  requirement.

Changes to the base schema:
- Replace the fixed clock/reset items lists with minItems/maxItems
  ranges; variant sub-schemas tighten the constraints via if-then-else.
- Add a 'port' property (graph.yaml single-port alias) alongside the
  existing 'ports', for single-output variants.
- Drop the unconditional 'ports' requirement; each if-branch enforces
  its own port topology.
- Tighten additionalProperties to unevaluatedProperties to allow
  per-variant schemas to add their own constraints cleanly.
- Fix a stray space in the port at 0 description.
- Add a DT example for the generic verisilicon,dc compatible
  (Nuvoton MA35D1 DCU Lite).

Signed-off-by: Joey Lu <a0987203069 at gmail.com>
---
 .../bindings/display/verisilicon,dc.yaml      | 135 ++++++++++++++----
 1 file changed, 108 insertions(+), 27 deletions(-)

diff --git a/Documentation/devicetree/bindings/display/verisilicon,dc.yaml b/Documentation/devicetree/bindings/display/verisilicon,dc.yaml
index 9dc35ab973f2..3a814c2e083e 100644
--- a/Documentation/devicetree/bindings/display/verisilicon,dc.yaml
+++ b/Documentation/devicetree/bindings/display/verisilicon,dc.yaml
@@ -14,10 +14,12 @@ properties:
     pattern: "^display@[0-9a-f]+$"
 
   compatible:
-    items:
-      - enum:
-          - thead,th1520-dc8200
-      - const: verisilicon,dc # DC IPs have discoverable ID/revision registers
+    oneOf:
+      - items:
+          - enum:
+              - thead,th1520-dc8200
+          - const: verisilicon,dc
+      - const: verisilicon,dc  # DC IPs have discoverable ID/revision registers
 
   reg:
     maxItems: 1
@@ -26,32 +28,24 @@ properties:
     maxItems: 1
 
   clocks:
-    items:
-      - description: DC Core clock
-      - description: DMA AXI bus clock
-      - description: Configuration AHB bus clock
-      - description: Pixel clock of output 0
-      - description: Pixel clock of output 1
+    minItems: 2
+    maxItems: 5
 
   clock-names:
-    items:
-      - const: core
-      - const: axi
-      - const: ahb
-      - const: pix0
-      - const: pix1
+    minItems: 2
+    maxItems: 5
 
   resets:
-    items:
-      - description: DC Core reset
-      - description: DMA AXI bus reset
-      - description: Configuration AHB bus reset
+    minItems: 1
+    maxItems: 3
 
   reset-names:
-    items:
-      - const: core
-      - const: axi
-      - const: ahb
+    minItems: 1
+    maxItems: 3
+
+  port:
+    $ref: /schemas/graph.yaml#/properties/port
+    description: Single video output port for single-output variants.
 
   ports:
     $ref: /schemas/graph.yaml#/properties/ports
@@ -59,7 +53,7 @@ properties:
     properties:
       port at 0:
         $ref: /schemas/graph.yaml#/properties/port
-        description: The first output channel , endpoint 0 should be
+        description: The first output channel, endpoint 0 should be
           used for DPI format output and endpoint 1 should be used
           for DP format output.
 
@@ -75,9 +69,75 @@ required:
   - interrupts
   - clocks
   - clock-names
-  - ports
 
-additionalProperties: false
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: thead,th1520-dc8200
+    then:
+      properties:
+        clocks:
+          items:
+            - description: DC Core clock
+            - description: DMA AXI bus clock
+            - description: Configuration AHB bus clock
+            - description: Pixel clock of output 0
+            - description: Pixel clock of output 1
+
+        clock-names:
+          items:
+            - const: core
+            - const: axi
+            - const: ahb
+            - const: pix0
+            - const: pix1
+
+        resets:
+          items:
+            - description: DC Core reset
+            - description: DMA AXI bus reset
+            - description: Configuration AHB bus reset
+
+        reset-names:
+          items:
+            - const: core
+            - const: axi
+            - const: ahb
+
+      required:
+        - ports
+
+    else:
+      properties:
+        clocks:
+          items:
+            - description: Bus clock that gates register access
+            - description: Pixel clock divider for display timing
+
+        clock-names:
+          items:
+            - const: core
+            - const: pix0
+
+        resets:
+          maxItems: 1
+          description:
+            Reset line for the display controller.
+
+        reset-names:
+          items:
+            - const: core
+
+      required:
+        - port
+
+      not:
+        required:
+          - ports
+
+unevaluatedProperties: false
 
 examples:
   - |
@@ -120,3 +180,24 @@ examples:
         };
       };
     };
+
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/clock/nuvoton,ma35d1-clk.h>
+    #include <dt-bindings/reset/nuvoton,ma35d1-reset.h>
+
+    display at 40260000 {
+        compatible = "verisilicon,dc";
+        reg = <0x40260000 0x20000>;
+        interrupts = <GIC_SPI 20 IRQ_TYPE_LEVEL_HIGH>;
+        clocks = <&clk DCU_GATE>, <&clk DCUP_DIV>;
+        clock-names = "core", "pix0";
+        resets = <&sys MA35D1_RESET_DISP>;
+        reset-names = "core";
+
+        port {
+            dpi_out: endpoint {
+                remote-endpoint = <&panel_in>;
+            };
+        };
+    };
-- 
2.43.0