Re: [Linuxptp-users] Interesting (very wrong) PTP output

[Keller, J. E <jac...@in...>]

> -----Original Message-----
> From: Richard Cochran [mailto:ric...@gm...]
> Sent: Wednesday, June 20, 2012 9:38 AM
> To: Christian Riesch
> Cc: jak...@in...; lin...@li...
> Subject: Re: [Linuxptp-users] Interesting (very wrong) PTP output
> 
> On Thu, Jun 07, 2012 at 11:54:48AM +0200, Christian Riesch wrote:
> 
> Even though Jacob had some other problem, I still am going to take this
> patch (or something similar) after I get a chance to test it.
> 
> I have a few comments...
> 
> > Please find below a patch (it's only an quick hack and only
> > compile-tested) that
> > a) sets the clock to 0 ppb before doing anything else,
> 
> Agreed, this should be done.
> 
> > b) clamps s->drift to the maximum adjustment value at the first
> calculation
> >    (estimation),
> 
> Not sure if this is too important, but I guess it doesn't hurt. If the
> actual drift is more than the max adjustment, then the situation is
> hopeless anyhow.
> 
> > c) applies the estimate to the clock.
> 
> Not sure if this is too important either. The drift will dominate this
> calculation in any case, right?
> 
> >  		ki_term = s->ki * offset;
> >  		ppb = s->kp * offset + s->drift + ki_term;
> 
> Thanks,
> Richard
> 
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I agree with the patch as well. My issue was different but this can help in odd cases (resetting the clock to 0ppb is good as that clears any previous settings)