nfb-mdio
The MDIO tool can be used, if the informations from the nfb-eth aren’t sufficient.
It allows to read and write specific MDIO registers in the PCS/PMA/PMD.
Addressing scheme corresponds to conventions in the IEEE802.3 clause 45.
For example turn on the PMA local loopback is done by nfb-mdio 1.0 1
.