dt-bindings: display: st: add two new compatibles to LTDC device

The new STMicroelectronics SoC features a display controller similar to
the one used in previous SoCs.  Because there is additional registers,
and different mandatory clocks it is incompatible with existing IPs.  On
STM32MP251, the device only needs two clocks while on STM32MP255 it
needs four.

Add the new names to the list of compatible string and handle each
quirks accordingly.

Acked-by: Philippe Cornu <philippe.cornu@foss.st.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20250822-drm-misc-next-v5-1-9c825e28f733@foss.st.com
Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>

Documentation/devicetree/bindings/display/st,stm32-ltdc.yaml

@@ -12,7 +12,10 @@ maintainers:
 
 properties:
   compatible:
-    const: st,stm32-ltdc
+    enum:
+      - st,stm32-ltdc
+      - st,stm32mp251-ltdc
+      - st,stm32mp255-ltdc
 
   reg:
     maxItems: 1
@@ -24,11 +27,16 @@ properties:
     minItems: 1
 
   clocks:
-    maxItems: 1
+    minItems: 1
+    maxItems: 4
 
   clock-names:
     items:
       - const: lcd
+      - const: bus
+      - const: ref
+      - const: lvds
+    minItems: 1
 
   resets:
     maxItems: 1
@@ -51,6 +59,46 @@ required:
   - resets
   - port
 
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - st,stm32-ltdc
+    then:
+      properties:
+        clocks:
+          maxItems: 1
+        clock-names:
+          maxItems: 1
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - st,stm32mp251-ltdc
+    then:
+      properties:
+        clocks:
+          minItems: 2
+          maxItems: 2
+        clock-names:
+          minItems: 2
+          maxItems: 2
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - st,stm32mp255-ltdc
+    then:
+      properties:
+        clocks:
+          minItems: 4
+        clock-names:
+          minItems: 4
+
 additionalProperties: false
 
 examples: