Yo Jacob E!
On Thu, 26 Feb 2015 17:41:16 +0000
"Keller, Jacob E" <jacob.e.kel...@intel.com> wrote:
> > > To be clear, linreg is just a linear regression servo which could
> > > control the system clock, if you were doing software
> > > timestamping. In this case linreg is controlling the hardware MAC
> > > clock.
> >
> > Hmm, that could be documented better. So the invisible hand inside
> > turns off the linreg->sysclock connection when hardware timestamping
> > enabled...
> >
>
> ....
>
> If you use software timestmaps you are controlling the clock that made
> those (software) timestamps.
>
> If you do hardware timestamps, you are controlling the clock that made
> those (hardware) timestamps.
>
> ptp4l controls one clock. Sometimes you get "lucky" in that you were
> doing software timestamps so it could directly control the software
> clock. You could also run in free-running mode so that it doesn't
> directly control the clock, or you could expose the timestamps as an
> NTP SHM and have ntp daemon control the clock.
Every time someone says 'the clock" I get lost. I got clocks all
over the place! System clock, hardware timestamp clock, NTP clock...
For now the only way I see to (easily) compare a good PPS clock to
either the the software timestamp clock or the hardware timestamp clock
is with NTP SHM. Otherwise hand computing jitter, offset, etc.
would be a PITA.
You got another easy calibration trick?
> > > > It is possible the PLL is going nuts on startup?
> > >
> > > It's probably due to starting in the weird state you did. If you
> > > let it run long enough it should stabilize.
> >
> > Weird state? What would you expect after a power cycle? The whole
> > point of an initialization is nothing is initialized yet!
> >
>
> You power cycled the machine?
Hardware troubleshooting 101, power cycle often.
> > > Try building it like "make M=Documentation/ptp/" from the top
> > > level.
> >
> > That worked. Maybe that should be documented?
>
> That is how the Kernel make system works. When you run make in the top
> level and name testphc, you are using implicit makefile rules, which
> is why it failed to build the -lrt library inclusion.
So that means it does not need to be documented? The Linux Documentation
tree is full of READMEs, just not in ptp. BUt I accept this is not the
right place to complain about that...
> > In any case, I have given up on the i217-LM. I have determined the
> > 82574L and the I210, on the same host, everything else identical
> > work fine for me.
Well, not so fine. The jitter on the 82574L is worse than NTP over the
same link and the I210 has a stubborn 833 mSec offset.
So I'm about to call three strikes and you are out.
> Yep. I'm hoping to get enough information so I can pass this on to the
> team that does the driver for the i27-LM and see if they can try to
> fix it :)
Great, thanks.
RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97701
g...@rellim.com Tel:+1(541)382-8588
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