Re: [PATCH net-next RFC 2/9] net: dsa: mv88e6xxx: expose switch time as a PTP hardware clock

On Fri, Sep 29, 2017 at 03:17:02PM +0000, Brandon Streiff wrote:

 
Although now that I'm looking it over again, I'm also not certain of
the need. Even if we're called more frequently than we expect, that
doesn't seem to be harmful with regard to timekeeping. Hmm.

Just keep it simple and drop the extra logic.  It doesn't hurt to
over-sample the clock.  Here is what I did:

/* Covers both a 100 or a 125 MHz input clock. */
#define MV88E635X_OVERFLOW_PERIOD (HZ * 16)

static void mv88e635x_overflow_check(struct work_struct *ws)
{
	struct timespec64 ts;
	struct mv88e6xxx_chip *ps =
		container_of(ws, struct mv88e6xxx_chip, oflow_work.work);

	mv88e635x_ptp_gettime(&ps->ptp_info, &ts);
	pr_debug("mv88e635x overflow check at %lld.%09lu\n",
		 ts.tv_sec, ts.tv_nsec);
	schedule_delayed_work(&ps->oflow_work, MV88E635X_OVERFLOW_PERIOD);
}

Thanks,
Richard