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Difference between revisions of "MX8 Display"

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VAR-SOM-MX8 supports DP, HDMI and LVDS displays. DP and HDMI require Variscite extension boards VAR-EXT-DP and VAR-EXT-HDMI.<br>
 
VAR-SOM-MX8 supports DP, HDMI and LVDS displays. DP and HDMI require Variscite extension boards VAR-EXT-DP and VAR-EXT-HDMI.<br>
 
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>
 
{{#lst:Yocto_Platform_Customization|{{#var:FDT_TABLE_SECTION}}}}
 
<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 it points to LVDS DTB.<br>
For example, to select HDMI display, run the following commands:
+
To select HDMI display, run the following commands:
  
 
  # cd /boot
 
  # cd /boot
 
  # ln -fs fsl-imx8qm-var-som-hdmi.dtb fsl-imx8qm-var-som.dtb
 
  # ln -fs fsl-imx8qm-var-som-hdmi.dtb fsl-imx8qm-var-som.dtb
 +
 +
To select DP display, run the following commands:
 +
 +
# cd /boot
 +
# ln -fs fsl-imx8qm-var-som-dp.dtb fsl-imx8qm-var-som.dtb
  
 
The change will be effective after reboot.<br>
 
The change will be effective after reboot.<br>
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HDMI and DP displays require appropriate firmware to be loaded by u-boot. The firmware files are installed under /boot.<br>
 
HDMI and DP displays require appropriate firmware to be loaded by u-boot. The firmware files are installed under /boot.<br>
 
The HDMI display firmware blob is hdmitxfw.bin, the DP firmware blob is dpfw.bin. U-Boot environment variable hdp_file selects the blob.<br>
 
The HDMI display firmware blob is hdmitxfw.bin, the DP firmware blob is dpfw.bin. U-Boot environment variable hdp_file selects the blob.<br>
By default HDMI firmware is loaded. To switch to DP firmware run the following command:
+
By default HDMI firmware is being loaded. To switch to DP firmware, run the following command:
  
 
  # fw_setenv hdp_file dpfw.bin
 
  # fw_setenv hdp_file dpfw.bin
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The change will be effective after reboot.<br>
 
The change will be effective after reboot.<br>
  
{{Note|Both firmware blob and DTB file should be set before rebooting the system, otherwise the boot process will be stuck.}}
+
{{Note|Both firmware blob and DTB file should be set before rebooting the system, otherwise the boot process will get stuck.}}
  
 
= Setting HDMI and DP resolution =
 
= Setting HDMI and DP resolution =
  
By default the maximum resolution supported by HDMI/DP display is used.<br>
+
By default the maximum resolution supported by HDMI/DP display is being used.<br>
 
To check the current resolution, run fbset command.
 
To check the current resolution, run fbset command.
 
<pre>
 
<pre>
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= LVDS =
 
= LVDS =
 
{{#var:HARDWARE_NAME}} supports one dual-channel LVDS interface.<br>
 
{{#var:HARDWARE_NAME}} supports one dual-channel LVDS interface.<br>
Variscite {{#var:HARDWARE_NAME}} evaluation kit comes with two LVDS connectors, one connector per LVDS channel.<br>
+
{{#var:HARDWARE_NAME}} evaluation kit comes with two LVDS connectors, one connector per LVDS channel.<br>
 
By default Variscite panel is attached to LVDS#A connector.<br>
 
By default Variscite panel is attached to LVDS#A connector.<br>
  
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To support different LVDS panel, several modifications may be required.
 
To support different LVDS panel, several modifications may be required.
  
The following code configures LVDS panel in arch/arm64/boot/dts/freescale/{{#ifeq: {{#var:HARDWARE_NAME}}|VAR-SOM-MX8X|fsl-imx8qxp-var-som-common.dtsi|fsl-imx8qm-var-som-lvds.dtsi}} under kernel source tree
+
The following code configures LVDS panel in arch/arm64/boot/dts/freescale/{{#ifeq: {{#var:HARDWARE_NAME}}|VAR-SOM-MX8X|fsl-imx8qxp-var-som-common.dtsi|fsl-imx8qm-var-som-lvds.dtsi}} under kernel source tree:
  
 
{{#ifeq: {{#var:HARDWARE_NAME}}|VAR-SOM-MX8X|
 
{{#ifeq: {{#var:HARDWARE_NAME}}|VAR-SOM-MX8X|

Revision as of 06:23, 15 September 2019


VAR-SOM-MX8X Display



1 LVDS

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