dt-bindings: display: Add idk-2121wr binding

Add binding for the idk-2121wr LVDS panel from Advantech.

Some panel-specific documentation can be found here:
https://buy.advantech.eu/Displays/Embedded-LCD-Kits-High-Brightness/model-IDK-2121WR-K2FHA2E.htmSigned-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1583869169-1006-1-git-send-email-prabhakar.mahadev-lad.rj@bp.renesas.com

Documentation/devicetree/bindings/display/panel/advantech,idk-2121wr.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/panel/advantech,idk-2121wr.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Advantech IDK-2121WR 21.5" Full-HD dual-LVDS panel
+
+maintainers:
+  - Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
+  - Thierry Reding <thierry.reding@gmail.com>
+
+description: |
+  The IDK-2121WR from Advantech is a Full-HD dual-LVDS panel.
+  A dual-LVDS interface is a dual-link connection with even pixels traveling
+  on one link, and with odd pixels traveling on the other link.
+
+  The panel expects odd pixels on the first port, and even pixels on the
+  second port, therefore the ports must be marked accordingly (with either
+  dual-lvds-odd-pixels or dual-lvds-even-pixels).
+
+properties:
+  compatible:
+    items:
+      - const: advantech,idk-2121wr
+      - {} # panel-lvds, but not listed here to avoid false select
+
+  width-mm:
+    const: 476
+
+  height-mm:
+    const: 268
+
+  data-mapping:
+    const: vesa-24
+
+  panel-timing: true
+
+  ports:
+    type: object
+    properties:
+      port@0:
+        type: object
+        description: The sink for odd pixels.
+        properties:
+          reg:
+            const: 0
+
+          dual-lvds-odd-pixels: true
+
+        required:
+          - reg
+          - dual-lvds-odd-pixels
+
+      port@1:
+        type: object
+        description: The sink for even pixels.
+        properties:
+          reg:
+            const: 1
+
+          dual-lvds-even-pixels: true
+
+        required:
+          - reg
+          - dual-lvds-even-pixels
+
+additionalProperties: false
+
+required:
+  - compatible
+  - width-mm
+  - height-mm
+  - data-mapping
+  - panel-timing
+  - ports
+
+examples:
+  - |+
+    panel-lvds {
+      compatible = "advantech,idk-2121wr", "panel-lvds";
+
+      width-mm = <476>;
+      height-mm = <268>;
+
+      data-mapping = "vesa-24";
+
+      panel-timing {
+        clock-frequency = <148500000>;
+        hactive = <1920>;
+        vactive = <1080>;
+        hsync-len = <44>;
+        hfront-porch = <88>;
+        hback-porch = <148>;
+        vfront-porch = <4>;
+        vback-porch = <36>;
+        vsync-len = <5>;
+      };
+
+      ports {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        port@0 {
+          reg = <0>;
+          dual-lvds-odd-pixels;
+          panel_in0: endpoint {
+            remote-endpoint = <&lvds0_out>;
+          };
+        };
+
+        port@1 {
+          reg = <1>;
+          dual-lvds-even-pixels;
+          panel_in1: endpoint {
+            remote-endpoint = <&lvds1_out>;
+          };
+        };
+      };
+    };
+
+...