This function forces the network interface into Master/Slave, without the user needing to know which registers to write to. This is particularly important for Single Pair Ethernet devices (SPE). In SPE communication, there needs to be a Master and Slave, both cannot be Master or Slave.

In the following codeblock, the ethtool command is used to check the current state of the PHY, then the state is changed to the other and checked again.

Command:

• ethtool -s ethx master-slave forced-master
• ethtool -s ethx master-slave forced-slave

root@j7-evm:~# ethtool eth3 | grep master-slave
        master-slave cfg: forced master
        master-slave status: master
root@j7-evm:~# ethtool -s eth3 master-slave forced-slave
root@j7-evm:~# ethtool eth3 | grep master-slave
        master-slave cfg: forced slave
        master-slave status: slave
root@j7-evm:~#