Dummy CRTC for Spreadtrum SoC
============================================================================

The dummy crtc is just used for engineer debug before realy chip bring-up.
There is a vsync timer in dummy crtc to send vblank event to userspace for
HW sync. This crtc can be connected to either a realy connector(DSI) or a
dummy connector. It is useful for HAPS/ZEBU platform development.
Note that the dummy crtc should not be used for product.

Required properties:
  - compatible: value should be "sprd,dummy-crtc";
  - port: a port node with endpoint definitions as defined in document [1].

[1]: Documentation/devicetree/bindings/media/video-interfaces.txt.


Example:

SoC specific DT entry:

	display-subsystem {
		compatible = "sprd,display-subsystem";
		ports = <&dummy_crtc_port>;
	};

	dummy-crtc {
		compatible = "sprd,dummy-crtc";

		dummy_crtc_port: port {
			dummy_crtc_out: endpoint {
				remote-endpoint = <&dummy_connector_in>;
			};
		};
	};


Board specific DT entry (if it has dpu & iommu node):

	&dpu {
		status = "disabled";
	};

	&iommu_dispc {
		status = "disabled";
	};

