xref: /openbmc/linux/Documentation/devicetree/bindings/display/bridge/megachips-stdpxxxx-ge-b850v3-fw.txt (revision 3eb66e91a25497065c5322b1268cbc3953642227)

Drivers for the second video output of the GE B850v3:
   STDP4028-ge-b850v3-fw bridges (LVDS-DP)
   STDP2690-ge-b850v3-fw bridges (DP-DP++)

The video processing pipeline on the second output on the GE B850v3:

   Host -> LVDS|--(STDP4028)--|DP -> DP|--(STDP2690)--|DP++ -> Video output

Each bridge has a dedicated flash containing firmware for supporting the custom
design. The result is that, in this design, neither the STDP4028 nor the
STDP2690 behave as the stock bridges would. The compatible strings include the
suffix "-ge-b850v3-fw" to make it clear that the driver is for the bridges with
the firmware specific for the GE B850v3.

The hardware do not provide control over the video processing pipeline, as the
two bridges behaves as a single one. The only interfaces exposed by the
hardware are EDID, HPD, and interrupts.

stdp4028-ge-b850v3-fw required properties:
  - compatible : "megachips,stdp4028-ge-b850v3-fw"
  - reg : I2C bus address
  - interrupts : one interrupt should be described here, as in
    <0 IRQ_TYPE_LEVEL_HIGH>
  - ports : One input port(reg = <0>) and one output port(reg = <1>)

stdp2690-ge-b850v3-fw required properties:
    compatible : "megachips,stdp2690-ge-b850v3-fw"
  - reg : I2C bus address
  - ports : One input port(reg = <0>) and one output port(reg = <1>)

Example:

&mux2_i2c2 {
	clock-frequency = <100000>;

	stdp4028@73 {
		compatible = "megachips,stdp4028-ge-b850v3-fw";
		#address-cells = <1>;
		#size-cells = <0>;

		reg = <0x73>;

		interrupt-parent = <&gpio2>;
		interrupts = <0 IRQ_TYPE_LEVEL_HIGH>;

		ports {
			#address-cells = <1>;
			#size-cells = <0>;

			port@0 {
				reg = <0>;
				stdp4028_in: endpoint {
					remote-endpoint = <&lvds0_out>;
				};
			};
			port@1 {
				reg = <1>;
				stdp4028_out: endpoint {
					remote-endpoint = <&stdp2690_in>;
				};
			};
		};
	};

	stdp2690@72 {
		compatible = "megachips,stdp2690-ge-b850v3-fw";
		#address-cells = <1>;
		#size-cells = <0>;

		reg = <0x72>;

		ports {
			#address-cells = <1>;
			#size-cells = <0>;

			port@0 {
				reg = <0>;
				stdp2690_in: endpoint {
					remote-endpoint = <&stdp4028_out>;
				};
			};

			port@1 {
				reg = <1>;
				stdp2690_out: endpoint {
					/* Connector for external display */
				};
			};
		};
	};
};