+  '#address-cells':
+    description: Number of address cells for the MDIO bus.
+    const: 1

Please could you explain this a bit more.

+
+  '#size-cells':
+    description: Number of size cells on the MDIO bus.
+    const: 0
+
+  ports:
+    type: object

I think ethernet-ports is the preferred name.

+
+required:
+  - compatible
+  - reg
+  - reg-names
+  - interrupts
+  - interrupt-names
+  - clocks
+  - clock-names
+  - resets
+  - power-domains
+  - '#address-cells'
+  - '#size-cells'

So ports are not required? You can have a 0 port switch?

   Andrew