Personal tools

VAR-SOM-MX6 LVDS Jethro

From Variscite Wiki

Jump to: navigation, search

VAR-SOM-MX6 - LVDS


1 LVDS on Variscite's EVKs

On VAR-SOLOCUSTOMBOARD and VAR-DT6CustomBoard:

  • LVDS1 is the primary default display, used as 18bit LVDS
  • LVDS0 is the the secondary display.

Note: On VAR-SOLOCUSTOMBOARD, LVDS0 and LVDS1 headers are not pin-2-pin compatible. Variscite's provided display can not be connected to LVDS0 header.

On VAR-MX6CUSTOMBOARD:

  • LVDS0 is the primary default display, used as 24bit LVDS, and connected to an RGB display, using LVDS->RGB converter.
  • LVDS1 is the the secondary display.

2 Resistive/Capacitive screen automatic selection on boot time

Automatic Device Tree selection

3 Switching between LVDS0 and LVDS1 as main display

Switching between the LVDS channels requires changing the location of the "primary" property to the desired lvds-channel sub-node of the ldb node in the device tree.
The relevant device tree source file for VAR-SOLOCUSTOMBOARD and VAR-DT6CustomBoard is arch/arm/boot/dts/imx6qdl-var-solocb-dt6cb-displays.dtsi,
for VAR-MX6CUSTOMBOARD with a capacitive touchscreen it's arch/arm/boot/dts/imx6qdl-var-mx6cb-cdisplay.dtsi
and for VAR-MX6CUSTOMBOARD with a resistive touchscreen it's arch/arm/boot/dts/imx6qdl-var-mx6cb-rdisplay.dtsi.

For Example:
To set the display to be LVDS0 by default on VAR-SOLOCUSTOMBOARD / VAR-DT6CustomBoard, edit arch/arm/boot/dts/imx6qdl-var-solocb-dt6cb-displays.dtsi and move the "primary" property from the lvds-channel@1 node to the lvds-channel@0 node.

	lvds-channel@0 {
		fsl,data-mapping = "spwg";
		fsl,data-width = <24>;
		crtc = "ipu1-di0";
		primary;
		status = "okay";

		display-timings {
			native-mode = <&timing0>;
			timing0: hsd100pxn1 {
				clock-frequency = <35714000>;
				hactive = <800>;
				vactive = <480>;
				hback-porch = <24>;
				hfront-porch = <15>;
				vback-porch = <13>;
				vfront-porch = <20>;
				hsync-len = <20>;
				vsync-len = <13>;
			};
		};
	};

Please take a look on the wiki section for kernel out of tree to see how to compile the device tree.