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DART-MX6 Parallel RGB Display

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DART-MX6 - Parallel RGB Display (lcd)


1 Kernel patch example

The following kernel patch activates the parallel display port, with RGB 24bit and with sample LCD settings defined as MY-LCD in drivers/video/fbdev/mxc/mxc_lcdif.c:

diff --git a/arch/arm/boot/dts/imx6q-var-dart.dts b/arch/arm/boot/dts/imx6q-var-dart.dts
index 355bd6d57bfe..8d4b6b7e3e50 100644
--- a/arch/arm/boot/dts/imx6q-var-dart.dts
+++ b/arch/arm/boot/dts/imx6q-var-dart.dts
@@ -158,15 +158,15 @@
 };
 
 &mxcfb2 {
-	status = "okay";
+	status = "disabled";
 };
 
 &mxcfb3 {
-	status = "okay";
+	status = "disabled";
 };
 
 &mxcfb4 {
-	status = "okay";
+	status = "disabled";
 };
 
 &sata {
diff --git a/arch/arm/boot/dts/imx6qdl-var-dart.dtsi b/arch/arm/boot/dts/imx6qdl-var-dart.dtsi
index fce2b66ac2d2..b2e0e4ea5c94 100644
--- a/arch/arm/boot/dts/imx6qdl-var-dart.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-var-dart.dtsi
@@ -114,8 +114,10 @@
 
 	mxcfb1: fb@0 {
 		compatible = "fsl,mxc_sdc_fb";
-		disp_dev = "ldb";
-		default_bpp = <16>;
+		disp_dev = "lcd";
+		interface_pix_fmt = "RGB24";
+		mode_str = "MY-LCD";
+		default_bpp = <24>;
 		int_clk = <0>;
 		late_init = <0>;
 		status = "disabled";
@@ -153,18 +155,18 @@
 		status = "disabled";
 	};
 
-#if 0
+
 	lcd@0 {
 		compatible = "fsl,lcd";
 		ipu_id = <0>;
 		disp_id = <0>;
-		default_ifmt = "RGB565";
+		default_ifmt = "RGB24";
 		pinctrl-names = "default";
 		pinctrl-0 = <&pinctrl_ipu1>;
 		status = "okay";
 	};
-#endif
 
+/*
 	backlight {
 		compatible = "pwm-backlight";
 		pwms = <&pwm2 0 50000>;
@@ -172,6 +174,7 @@
 		default-brightness-level = <7>;
 		status = "okay";
 	};
+*/
 
 	v4l2_cap_0 {
 		compatible = "fsl,imx6q-v4l2-capture";
@@ -422,11 +425,13 @@
 			>;
 		};
 
+/*
 		pinctrl_pwm1_1: pwm1grp {
 			fsl,pins = <
 				MX6QDL_PAD_DISP0_DAT9__PWM2_OUT		0x1b0b1
 			>;
 		};
+*/
 
 		/* Linux Console */
 		pinctrl_uart1_1: uart1grp-1 { /* RX/TX only */
@@ -632,12 +637,13 @@
 	status = "okay";
 };
 
+/*
 &pwm2 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_pwm1_1>;
 	status = "okay";
 };
-
+*/
 
 &ssi2 {
 	fsl,mode = "i2s-slave";
diff --git a/arch/arm/boot/dts/imx6qdl-var-solocb-dt6cb-displays.dtsi b/arch/arm/boot/dts/imx6qdl-var-solocb-dt6cb-displays.dtsi
index b2f28504344e..951a6fb4163b 100644
--- a/arch/arm/boot/dts/imx6qdl-var-solocb-dt6cb-displays.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-var-solocb-dt6cb-displays.dtsi
@@ -14,9 +14,6 @@
  * Capacitive Display for VAR-SoloCustomBoard and VAR-DT6CustomBoard
  */
 
-&mxcfb1 {
-	interface_pix_fmt = "RGB666";
-};
 
 &i2c3 {
 	touch: ft5x06_ts@38 {
@@ -28,13 +25,13 @@
 };
 
 &ldb {
-	status = "okay";
+	status = "disabled";
 
 	lvds-channel@0 {
 		fsl,data-mapping = "spwg";
 		fsl,data-width = <24>;
 		crtc = "ipu1-di0";
-		status = "okay";
+		status = "disabled";
 
 		display-timings {
 			native-mode = <&timing0>;
@@ -57,7 +54,7 @@
 		fsl,data-width = <18>;
 		crtc = "ipu1-di1";
 		primary;
-		status = "okay";
+		status = "disabled";
 
 		display-timings {
 			native-mode = <&timing1>;
diff --git a/drivers/video/fbdev/mxc/mxc_lcdif.c b/drivers/video/fbdev/mxc/mxc_lcdif.c
index 59d429c82017..6bcd941cb599 100644
--- a/drivers/video/fbdev/mxc/mxc_lcdif.c
+++ b/drivers/video/fbdev/mxc/mxc_lcdif.c
@@ -48,6 +48,12 @@ static struct fb_videomode lcdif_modedb[] = {
 	FB_SYNC_CLK_LAT_FALL,
 	FB_VMODE_NONINTERLACED,
 	0,},
+	{
+	/* 1280x1024 @ 60 Hz , pixel clk @ 54MHz */
+	"MY-LCD", 60, 1280, 1024, 18519, 248, 48, 38, 1, 112, 3,
+	FB_SYNC_CLK_LAT_FALL,
+	FB_VMODE_NONINTERLACED,
+	0,},
 };
 static int lcdif_modedb_sz = ARRAY_SIZE(lcdif_modedb);

2 Customizing the example for your specific LCD

To set the LCD parameters from a specific LCD data sheet:
In the patch, look at the definition of MY-LCD in drivers/video/fbdev/mxc/mxc_lcdif.c - and change its parameters.
Its type is the following struct (defined in include/linux/fb.h):

struct fb_videomode {
        const char *name;       /* optional */
        u32 refresh;            /* optional */
        u32 xres;
        u32 yres;
        u32 pixclock;
        u32 left_margin;
        u32 right_margin;
        u32 upper_margin;
        u32 lower_margin;
        u32 hsync_len;
        u32 vsync_len;
        u32 sync;
        u32 vmode;
        u32 flag;
};

Note that pixclock's units are picoseconds and not MHz.

vmode accepts bitwise or combinations of FB_VMODE_* definitions
sync accepts bitwise or combinations of FB_SYNC_* definitions.

FB_VMODE_NONINTERLACED - Non interlaced video
FB_SYNC_CLK_LAT_FALL - Negative polarity of pixel clock
FB_SYNC_OE_LOW_ACT - Invert polarity of data enable
FB_SYNC_HOR_HIGH_ACT - Invert polarity of HSYNCH
FB_SYNC_VERT_HIGH_ACT - Invert polarity of VSYNCH

3 Needed U-Boot environment change

To use this sample LCD configuration, a change is needed also in the videoargs variable in the U-Boot environment:
Change the current definition of video=mxcfb0 to video=mxcfb0:dev=lcd,MY-LCD,if=RGB24.