Transceiver Toolkit - "locked" indicators

With a properly functioning link you should never loose lock to data. With a reasonable channel you could see occasional data errors, how often is an indication of the quality of the channel and the RX/TX eq settings, but not lock to data dropping out.

When locked to data is set the locked to ref is a dont care. It is possible to spuriously report lock to data briefly due to picking up noise if the inputs are floating or at a signal that is not at the correct frequency. If you have a good steady state signal on the data and lock to ref is still fluctuating then your refclk is not high quality and all bets are off.