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Selecting display configuration is a matter of selecting an appropriate DTB file.<br>
 
Selecting display configuration is a matter of selecting an appropriate DTB file.<br>
 
All available DTB files are listed in the table below.<br>
 
All available DTB files are listed in the table below.<br>
{| class="wikitable"
+
 
|-
+
! scope="col" | DTB File Name<br/>
+
! scope="col" | Description<br/>
+
|-
+
| style="padding: 5px;"| fsl-imx8qm-var-som-dp.dtb
+
| style="padding: 5px;"| Device tree blob for Display Port display
+
|-
+
| style="padding: 5px;"| fsl-imx8qm-var-som-hdmi.dtb
+
| style="padding: 5px;"| Device tree blob for HDMI display
+
|-
+
| style="padding: 5px;"| fsl-imx8qm-var-som-lvds.dtb
+
| style="padding: 5px;"| Device tree blob for LVDS display
+
|-
+
|}
+
 
<br>
 
<br>
 
File /boot/fsl-imx8qm-var-som.dtb is a symbolic link to the active DTB file. By default LVDS display is used.<br>
 
File /boot/fsl-imx8qm-var-som.dtb is a symbolic link to the active DTB file. By default LVDS display is used.<br>

Revision as of 05:43, 15 September 2019


VAR-SOM-MX8X Display



1 LVDS

VAR-SOM-MX8X supports one dual-channel LVDS interface.
Variscite VAR-SOM-MX8X 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

VAR-SOM-MX8X evaluation kit comes with 800x480 LVDS panel.
VAR-SOM-MX8X DTS file was created with this panel in mind.
To support different LVDS panel, several modifications may be required.

The following code configures LVDS panel in arch/arm64/boot/dts/freescale/fsl-imx8qxp-var-som-common.dtsi under kernel source tree

&ldb1_phy {
	status = "ok";
};

&ldb1 {
	status = "ok";
	lvds-channel@0 {
		fsl,data-mapping = "jeida";
		fsl,data-width = <24>;
		status = "ok";

		display-timings {
			lvds {
				clock-frequency = <29232000>;
				hactive = <800>;
				vactive = <480>;
				hback-porch = <40>;
				hfront-porch = <40>;
				vback-porch = <29>;
				vfront-porch = <13>;
				hsync-len = <48>;
				vsync-len = <3>;
				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, to set 1080P resolution

[shell]
size=3840x2160

For new settings to take effect restart weston by running

# systemctl restart weston