Florian Fainelli [off-list ref] writes:

On 04/25/2017 04:53 PM, Eric Anholt wrote:

quoted

Cygnus has a single AMAC controller connected to the B53 switch with 2
PHYs.  On the BCM911360_EP platform, those two PHYs are connected to
the external ethernet jacks.

Signed-off-by: Eric Anholt <redacted>
Reviewed-by: Florian Fainelli <redacted>
---

v2: Call the node "switch", just call the ports "port" (suggestions by
    Florian), drop max-speed on the phys (suggestion by Andrew Lunn),
    call the other nodes "ethernet" and "ethernet-phy" (suggestions by
    Sergei Shtylyov)

 arch/arm/boot/dts/bcm-cygnus.dtsi      | 58 ++++++++++++++++++++++++++++++++++
 arch/arm/boot/dts/bcm911360_entphn.dts |  8 +++++
 2 files changed, 66 insertions(+)

diff --git a/arch/arm/boot/dts/bcm-cygnus.dtsi b/arch/arm/boot/dts/bcm-cygnus.dtsi
index 009f1346b817..9fd89be0f5e0 100644
--- a/arch/arm/boot/dts/bcm-cygnus.dtsi
+++ b/arch/arm/boot/dts/bcm-cygnus.dtsi

@@ -142,6 +142,54 @@
 			interrupts = <0>;
 		};
 
+		mdio: mdio@18002000 {
+			compatible = "brcm,iproc-mdio";
+			reg = <0x18002000 0x8>;
+			#size-cells = <1>;
+			#address-cells = <0>;

Sorry for not noticing earlier, since you override this correctly in the
board-level DTS file can you put a:

			status = "disabled"

property in there by default?

I didn't have the override in the board file either, just switch and
ethernet.  Fixed.