[PATCH v2] dt-bindings: display: imx: Document fsl,pcr

[Fabio Estevam <festevam@gmail.com>]

Some i.MX25 and i.MX27 devicetree display nodes contain fsl,pcr, but
the property has no schema type. As a result, dt-core.yaml reports
its raw bytes as an invalid property:

  imx27-phytec-phycard-s-rdk.dtb: display: fsl,pcr:
  b'\xf0\xc8\x80\x80' is not of type
  'object', 'integer', 'array', 'boolean', 'null'

Document fsl,pcr as a uint32. The property belongs to the display node
referenced by the display phandle and is not valid on the LCD controller
node.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
---
Changes since v1:
- Explicitly forbid fsl,pcr on the controller through allOf, addressing
  the Sashiko review, while retaining its uint32 type for decoding the
  property in legacy display nodes.

 .../devicetree/bindings/display/imx/fsl,imx-lcdc.yaml  | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/imx/fsl,imx-lcdc.yaml b/Documentation/devicetree/bindings/display/imx/fsl,imx-lcdc.yaml
index 84610b5690c4..450f95098c99 100644
--- a/Documentation/devicetree/bindings/display/imx/fsl,imx-lcdc.yaml
+++ b/Documentation/devicetree/bindings/display/imx/fsl,imx-lcdc.yaml
@@ -65,7 +65,17 @@ properties:
     description:
       LCDC Sharp Configuration Register value.
 
+  fsl,pcr:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      LCDC Panel Configuration Register value used in the display node
+      referenced by the display property.
+
 allOf:
+  # Define the type above for decoding, but forbid it on the controller.
+  - properties:
+      fsl,pcr: false
+
   - if:
       properties:
         compatible: