MX8 Display: Difference between revisions

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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 14:23, 15 September 2019

VAR-SOM-MX8X Display


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.

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.

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