Documentation/devicetree/bindings/display/virtual-encoder.txt

DRM Virtual Encoder

The DRM Virtual Encoder is a component-based basic encoder that fetches
the display timings information from the device tree and "discovers" a
DRM output with the given data. It is helpful in a simulated environment
where there is no actual hardware to be probed and the configuration of
the display happens outside the kernel world.

Required properties:
  - compatible: should be "drm,virtual-encoder"

Required sub-nodes:
  - display-timings: node describing the virtual output timings information,
    as specified in panel/display-timing.txt file.
  - port: the input port connection as modelled using the OF graph bindings
    specified in Documentation/devicetree/bindings/graph.txt


Example:

/ {
	...

	vencoder {
		compatible = "drm,virtual-encoder";
		display-timings {
			native-mode = <&timing1>;
			timing0: timing@0 {
				/* 640x480 framebuffer */
				clock-frequency = <23750>;
				hactive = <640>;
				vactive = <480>;
				hfront-porch = <48>;
				hback-porch = <16>;
				hsync-len = <96>;
				vfront-porch = <33>;
				vback-porch = <9>;
				vsync-len = <3>;
			};
			timing1: timing@1 {
				/* 1280x720 framebuffer */
				clock-frequency = <74440000>;
				hactive = <1280>;
				vactive = <720>;
				hfront-porch = <56>;
				hback-porch = <192>;
				hsync-len = <136>;
				vfront-porch = <1>;
				vback-porch = <22>;
				vsync-len = <3>;
			};
		};

		port {
			vencoder_in: endpoint {
				remote-endpoint = <&driver_out>;
			};
		};
	};

	drm_driver: driver@f00bad {
		...

		port {
			driver_out: endpoint {
				remote-endpoint = <&vencoder_in>;
			};
		};

		...
	};

	...
};