Re: [Linuxptp-users] grandmaster with an H/P 3805A GPS disciplined osc

[Richard C. <ric...@gm...>]

On Wed, Aug 21, 2013 at 03:38:26PM -0700, David Gravereaux wrote:
> 
> Conceptually, yes, I want to train the high-res clock of the i210 from
> the radio.  And from that, or maybe in parallel with, train the system
> clock.

Okay.
 
> First, I don't understand what phc2sys is used for.  If I'm running the
> ptp4l daemon as a slave with free-running off, the daemon is setting and
> training system clock, yes?

No, just /dev/ptp0.

The phc2sys program is for syncing CLOCK_REALTIME to /dev/ptp0.

[ But if you select SW time stamping, then ptp4l will discipline
  CLOCK_REALTIME instead of /dev/ptp0. In that case, you don't need to
  run phc2sys at all. ]

> Or is it just the clock of the controller?

Yes.

> Now if I'm using ptp as a grandmaster, who trains the /dev/ptp0 and how?

(That would be the program that you are going to write ;)

>  Or if I'm driving a PPS input at the comport's DCD line that NTPd is
> using through its atom driver to /dev/pps0, is this managed by ptp4l for
> slewing the card's clock?

No, it is not managed by ptp4l. You have to make sure that, if run
them at the same time, ntpd and ptp4l/phc2sys do not step on each
other's toes.

> Yeah, I'm lost.

I think you are on the right track. (At least you are asking the right
questions :)

Thanks,
Richard