ClearFog Base -- "status: no carrier" for mvneta1

[glenn]

With a recent build from source (FreeBSD  12.0-ALPHA7 FreeBSD 12.0-ALPHA7 7fe1a714461(master) ARMADA38X  arm) the ethernet port on a ClearFog Base near the USB sockets works well, but the port near the SFP cage doesn’t. ifconfig shows "mvneta1: status: no carrier”. 

Both ports are connected to a gigabit switch. The green link LED on the ClearFog Base for mvneta0 is on most of the time, but flickering; the green link LED for mvneta1 is on without flickering. On the switch, the corresponding link LED for mvneta0 is on constantly, the LED for mvneta1 is off. 

I don’t believe it’s a hardware issue, because, if the patch cables are swapped at the board, mvneta1 still shows no carrier and which LED on the switch is illuminated swaps. Also, without touching the cables or switch, Debian can be booted up using a different SD card, and both ethernet ports are functional with no special action taken.

The device tree file being used is compiled from armada-388-clearfog-base.dts in the FreeBSD source, but edited to allow the serial console to work.

What might it take to get that second ethernet port to work? A modification of the device tree file? A modification of the mvneta or miibus driver? A modification of u-boot? Or, perhaps, just a simple configuration step?

Glenn