MX8 Display

From Variscite Wiki
Display


1 LVDS

supports one dual-channel LVDS interface.
evaluation kit comes with two LVDS connectors, one connector per LVDS channel.

By default Variscite panel is attached to LVDS#A connector.

1.1 Adding custom LVDS panel

evaluation kit comes with 800x480 LVDS panel. 
DTS file was created with this panel in mind.

To support different LVDS panel, several modifications may be required.

On VAR-SOM-MX8 LVDS panel is configured in arch/arm64/boot/dts/freescale/fsl-imx8qm-var-som-lvds.dtsi
On SPEAR-MX8 LVDS panel is configured in arch/arm64/boot/dts/freescale/fsl-imx8qm-var-spear-lvds.dtsi

&ldb1_phy {
	status = "okay";
};

&ldb1 {
	status = "okay";

	lvds-channel@0 {
		fsl,data-mapping = "spwg";
		fsl,data-width = <18>;
		status = "okay";

		display-timings {
			lvds {
				clock-frequency = <35714000>;
				hactive = <800>;
				vactive = <480>;
				hback-porch = <39>;
				hfront-porch = <39>;
				vback-porch = <29>;
				vfront-porch = <13>;
				hsync-len = <47>;
				vsync-len = <2>;
				hsync-active = <0>;
				vsync-active = <0>;
				de-active = <1>;
				pixelclk-active = <0>;
			};
		};
	};
};

You may need to modify "fsl,data-mapping", "fsl,data-width" and "display-timings" properties to match your panel specification.
For more information see Documentation/devicetree/bindings/display/imx/ldb.txt in the kernel source tree.

2 Setting Weston Desktop Resolution

The default Weston uses maximum resolution supported by display.
To modify Weston resolution, edit /etc/xdg/weston/weston.ini and set size parameter in shell section.
For example:

[shell]
size=3840x2160

For new settings to take effect restart weston by running

# systemctl restart weston