When ptp4l detects a fault, the application stops for a short time until
the fault_reset_interval has passed.
Since commit 3b82f227ce96 ("clock: Monitor the link status using a RT
netlink socket."), the clock state machine will not try to restart a port
when link is down. This makes sense because
If ptp4l received a signal in poll() waiting for a transmit timestamp,
multiple (possibly confusing) error messages are logged before exit.
If poll() returns with EINTR, call it once again to get the timestamp
and avoid logging the errors. Don't call it in a loop to avoid getting
stuck in case the
