Yes. adj_freq is for sub nanosecond adjustments. Let's say your clock was r=
unning
off by 100 nanoseconds every billion. That means that for every 1 second yo=
u add
an additional 100 ns that you shouldn't be. You need to be able to do these=
minor
adjustments in order to prevent drift. If you only correct offset, then eve=
ry 1
second you will have another 100ns to add. You can get even worse, say you =
were
off by like 1-2 milliseconds every second. You really need to be able to ma=
nage
frequency changes on a very small scale in order to adjust for drift.

Thanks

- Jake
=20