Benjamin Herrenschmidt spake unto us the following wisdom:
Something else you can try: in arch/ppc/kernel/pmac_time.c, comment
out the call to via_calibrate_decr() (and the return too) so that
we use the device-tree "timebase-frequency" instead, and tell us if
it makes any difference.
That seems to have improved it *greatly*. I know have a drift (only
sampled after a few minutes, so somewhat inaccurate -- but accurate
enough to tell that it's no longer seconds/minute) more on a par with
what I have come to expect.
Ethan
--
If I've told you once, I've told you once
And once is all that you needed.
-- The Refreshments, "Carefree"