Documentation for boards with KSZ9031 phy

[polprog]

Some zturn boards have a ksz9031rnx ethernet phy installed instead of ar8035. They look identically take for the RJ jack area, the ksz9031 is larger package. The boards that we have use xc7z020. I think it is worth to document this, as the change is not reflected in the schematics on Myir's website, nor anywhere else that I've seen. I have a working Petalinux set up for this variant of the board - it needs to have the devicetree modified.

Im not sure where exactly is the "bug" (is it Petalinux or this repo), but I've used the files from this repo to prepare a minimal PS7 box using the TCL automation, then export the hardware description file with Vivado and then initialize the Petalinux project with that. The generated vanilla configuration did not have a working ethernet interface, which I think is wrong.

I can provide more information and I will be posting the steps necesary to get the ethernet iface working on the ksz9031-equipped boards soon (i need to write my thoughts and sources down in one file)

[polprog]

KZ9031 boards can be used with the following dtsi:

	/delete-node/ gem0;
	ethernet@e000b000 {
			compatible = "cdns,zynq-gem", "cdns,gem";
			reg = <0xe000b000 0x1000>;
			status = "okay";
			interrupts = <0x00 0x16 &intc>;
			clocks = <&clkc 30>, <&clkc 30>, <&clkc 13>;
			clock-names = "pclk", "hclk", "tx_clk";
			#address-cells = <0x01>;
			#size-cells = <0x00>;
			phy-mode = "rgmii-id";
			#enet-reset = <&gpio0 51 0>;
			xlnx,ptp-enet-clock = <0x69f6bcb>;
			phy-handle = <&phy0>;
			xlnx,has-mdio = <0x1>;
			xlnx,eth-mode = <0x1>;

			fixed-link{
				speed = <1000>;
				full-duplex;
			};

			mdio {
				phy0: ethernet-phy@0 {
					compatible = "micrel,ksz9031";
					device-type= "ethernet-phy";
					reg = <0x03>;
					micrel,reg-init = <0x3 0x12 0x7fff 0x880>;
				};
			};
		};
	};

reg-init as per https://forums.developer.nvidia.com/t/rgmii-doesnt-work-with-ksz9031/237927 .
Leaving out the fixed speed stanza in the device tree causes the interface to not work after boot unless the cable is unplugged and plugged back in.