Differences between LAN7800 and LAN7850 from the driver's perspective:
* The LAN7800 muxes EEPROM signals with LEDs, so LED mode needs to be
disabled when reading/writing EEPROM. The EEPROM is not muxed on the
LAN7850.
* The Linux driver enables automatic duplex and speed detection when
there is no EEPROM, for the LAN7800 only. With this FreeBSD driver
LAN7850-based adapters without a configuration EEPROM fail to link
(with or without the automatic duplex and speed detection code), so
I have just followed the example of the Linux driver for now.
Sponsored by: The FreeBSD Foundation
Sponsored by: Microchip (hardware)