+			port@4 {
+				reg = <4>;
+				ethernet = <&fec>;
+				label = "cpu";
+				phy-mode = "rgmii-id";
+				rx-internal-delay-ps = <2000>;
+				tx-internal-delay-ps = <2000>;
+
+				fixed-link {
+					full-duplex;
+					speed = <100>;
+				};
+			};
+		};
+	};
+};
+
+&fec {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_fec>;
+	phy-mode = "rgmii"; /* switch inserts delay */
+	rx-internal-delay-ps = <0>;
+	tx-internal-delay-ps = <0>;
+	status = "okay";
+
+	fixed-link {
+		full-duplex;
+		speed = <100>;
+	};

You have an RGMII interface, but you run it at 100Mbps? That might be
worth a comment somewhere to explain why.

	Andrew