[D18] add LVDS WVGA single-channel video support

* enabled at u-boot: seco_config tool
* connected on LVDS channel 1
* on CSB79REVB: panel URT UMSH-8596MD-20T + CV1338/400REVB
  (LVDS CN14+LCD CN17: switch SW6 1-3 position OFF, jumper CN20
  position 1-2 and CN21 position 1-2)

arch/arm64/boot/dts/seco/overlays/Makefile

@@ -26,6 +26,7 @@ dtbo-$(CONFIG_ARCH_MXC) += \
 	seco-imx8qm-c43-lvds-sn65dsi86.dtbo\
 	seco-imx8mp-d18-hdmi.dtbo\
 	seco-imx8mp-d18-lvds-fhd.dtbo\
+	seco-imx8mp-d18-lvds-wvga.dtbo\
 	seco-imx8mp-d18-audio-btsco.dtbo
 
 	# seco-imx8qm-c26-dp.dtbo\

arch/arm64/boot/dts/seco/overlays/seco-imx8mp-d18-lvds-wvga-overlay.dts

+/*
+ * Copyright 2021 SECO
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <dt-bindings/gpio/gpio.h>
+
+/dts-v1/;
+/plugin/;
+
+/ {
+	compatible = "fsl,imx8mp-evk", "seco,imx8mp-d18", "fsl,imx8mp";
+
+/*  __________________________________________________________________________
+ * |                                                                          |
+ * |                               LVDS                                       |
+ * |__________________________________________________________________________|
+ */
+
+	fragment@0 {
+		target-path = "/";
+		__overlay__ {
+			panel_lvds_wvga: lvds_panel_wvga {
+				#address-cells = <1>;
+				#size-cells = <0>;
+				compatible = "seco,seco-800x480";
+				status = "okay";
+
+				port {
+					panel_lvds_wvga_in: endpoint {
+						remote-endpoint = <&lvds_wvga_out>;
+					};
+				};
+			};
+		};
+	};
+
+	fragment@1 {
+		target = <&ldb>;
+		__overlay__ {
+			#address-cells = <1>;
+			#size-cells = <0>;
+			status = "okay";
+
+			lvds-channel@1 {
+				#address-cells = <1>;
+				#size-cells = <0>;
+				status = "okay";
+
+				/delete-node/ port@1;
+
+				port@1 {
+					reg = <1>;
+					#address-cells = <1>;
+					#size-cells = <0>;
+					lvds_wvga_out: endpoint {
+						remote-endpoint = <&panel_lvds_wvga_in>;
+					};
+				};
+			};
+		};
+	};
+
+	fragment@2 {
+		target = <&lcdif2>;
+		__overlay__ {
+			status = "okay";
+		};
+	};
+
+	fragment@3 {
+		target = <&ldb_phy>;
+		__overlay__ {
+			status = "okay";
+		};
+	};
+
+	fragment@4 {
+		target-path = "/";
+		__overlay__ {
+			reg_lcd1_vdd_en: regulator-lcd1-vdd-en {
+				compatible = "regulator-fixed";
+				regulator-name = "lcd1_vdd_en";
+				regulator-min-microvolt = <3300000>;
+				regulator-max-microvolt = <3300000>;
+				gpio = <&pca6416 7 0>;
+				enable-active-high;
+				regulator-always-on;
+				regulator-boot-on;
+				status = "okay";
+			};
+
+			reg_lcd1_bkl_en: regulator-lcd1-bkl-en {
+				compatible = "regulator-fixed";
+				regulator-name = "lcd1_bkl_en";
+				regulator-min-microvolt = <3300000>;
+				regulator-max-microvolt = <3300000>;
+				gpio = <&pca6416 6 0>;
+				enable-active-high;
+				regulator-always-on;
+				regulator-boot-on;
+				status = "okay";
+			};
+		};
+	};
+
+	fragment@5 {
+		target-path = "/";
+		__overlay__ {
+			lcd1_backlight {
+				compatible = "pwm-backlight";
+				pwms = <&pwm4 0 100000>;
+				status = "okay";
+
+				brightness-levels = <0 100>;
+				num-interpolated-steps = <100>;
+				default-brightness-level = <80>;
+			};
+		};
+	};
+
+};