dt-bindings: display: bridge: Add i.MX8qm/qxp display pixel link binding

This patch adds bindings for i.MX8qm/qxp display pixel link.
Signed-off-by: Liu Ying <victor.liu@nxp.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220611141421.718743-6-victor.liu@nxp.com

Documentation/devicetree/bindings/display/bridge/fsl,imx8qxp-pixel-link.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/bridge/fsl,imx8qxp-pixel-link.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Freescale i.MX8qm/qxp Display Pixel Link
+
+maintainers:
+  - Liu Ying <victor.liu@nxp.com>
+
+description: |
+  The Freescale i.MX8qm/qxp Display Pixel Link(DPL) forms a standard
+  asynchronous linkage between pixel sources(display controller or
+  camera module) and pixel consumers(imaging or displays).
+  It consists of two distinct functions, a pixel transfer function and a
+  control interface.  Multiple pixel channels can exist per one control channel.
+  This binding documentation is only for pixel links whose pixel sources are
+  display controllers.
+
+  The i.MX8qm/qxp Display Pixel Link is accessed via System Controller Unit(SCU)
+  firmware.
+
+properties:
+  compatible:
+    enum:
+      - fsl,imx8qm-dc-pixel-link
+      - fsl,imx8qxp-dc-pixel-link
+
+  fsl,dc-id:
+    $ref: /schemas/types.yaml#/definitions/uint8
+    description: |
+      u8 value representing the display controller index that the pixel link
+      connects to.
+
+  fsl,dc-stream-id:
+    $ref: /schemas/types.yaml#/definitions/uint8
+    description: |
+      u8 value representing the display controller stream index that the pixel
+      link connects to.
+    enum: [0, 1]
+
+  ports:
+    $ref: /schemas/graph.yaml#/properties/ports
+
+    properties:
+      port@0:
+        $ref: /schemas/graph.yaml#/properties/port
+        description: The pixel link input port node from upstream video source.
+
+    patternProperties:
+      "^port@[1-4]$":
+        $ref: /schemas/graph.yaml#/properties/port
+        description: The pixel link output port node to downstream bridge.
+
+    required:
+      - port@0
+      - port@1
+      - port@2
+      - port@3
+      - port@4
+
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: fsl,imx8qxp-dc-pixel-link
+    then:
+      properties:
+        fsl,dc-id:
+          const: 0
+
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: fsl,imx8qm-dc-pixel-link
+    then:
+      properties:
+        fsl,dc-id:
+          enum: [0, 1]
+
+required:
+  - compatible
+  - fsl,dc-id
+  - fsl,dc-stream-id
+  - ports
+
+additionalProperties: false
+
+examples:
+  - |
+    dc0-pixel-link0 {
+        compatible = "fsl,imx8qxp-dc-pixel-link";
+        fsl,dc-id = /bits/ 8 <0>;
+        fsl,dc-stream-id = /bits/ 8 <0>;
+
+        ports {
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            /* from dc0 pixel combiner channel0 */
+            port@0 {
+                reg = <0>;
+
+                dc0_pixel_link0_dc0_pixel_combiner_ch0: endpoint {
+                    remote-endpoint = <&dc0_pixel_combiner_ch0_dc0_pixel_link0>;
+                };
+            };
+
+            /* to PXL2DPIs in MIPI/LVDS combo subsystems */
+            port@1 {
+                #address-cells = <1>;
+                #size-cells = <0>;
+                reg = <1>;
+
+                dc0_pixel_link0_mipi_lvds_0_pxl2dpi: endpoint@0 {
+                    reg = <0>;
+                    remote-endpoint = <&mipi_lvds_0_pxl2dpi_dc0_pixel_link0>;
+                };
+
+                dc0_pixel_link0_mipi_lvds_1_pxl2dpi: endpoint@1 {
+                    reg = <1>;
+                    remote-endpoint = <&mipi_lvds_1_pxl2dpi_dc0_pixel_link0>;
+                };
+            };
+
+            /* unused */
+            port@2 {
+                reg = <2>;
+            };
+
+            /* unused */
+            port@3 {
+                reg = <3>;
+            };
+
+            /* to imaging subsystem */
+            port@4 {
+                reg = <4>;
+            };
+        };
+    };