[LinuxPPS] PPS/ntpd fails on fresh startup

[Hal V. Engel]

On Monday 13 October 2008 06:47:23 Luca Bertagnolio wrote:
> Rodolfo, when you have a minute can you comment on my issue?
>
> Why would LinuxPPS fail at the first startup, and work the second time?
>
> Thanks, Luca

I have this happen to me as well on occasion, perhaps 5% of the time from a 
cold system start and never once the system is running.  It just happened to 
me this morning however.  So Luca is not the only one seeing this but I think 
he may be the only one seeing this on every system restart.

I have an LED attached to my PPS signal and I can tell when it is being 
initialized by the driver since the LED will stop flashing for perhaps 20 
seconds and when this fails at start up the driver does NOT initialize the GPS 
(IE. the LED does not stop flashing).  I don't know what this tells us about 
this issue.  In my case it is intermittent which makes difficult to diagnose.

Hal

>
> On Tue, Oct 7, 2008 at 2:08 AM, Luca Bertagnolio <time at berta.com> wrote:
> > Reg,
> >
> >> Try putting a 'sleep 5' after the section with ppsldisc, and before
> >> starting ntpd.
> >>
> >> Its ugly, but it should work.
> >> The problem is that it takes the system some time to set up the ldisc,
> >> and it probably isnt worth trying to wait (cleanly) for this to happen. 
> >> In your init startup you get to the point where you need the pps device
> >> before its available.
> >>
> >> In any case, works for me...
> >
> > it doesn't for me.  From the dmesg log, looks like ppsldisc starts to
> > work OK with the script sleeping for 5 seconds, then as soon as ntpd
> > starts, the same as before happens:
> >
> > source serial1 got cdev (253:0)
> > new PPS source serial1 at ID 0
> > PPS source #0 "/dev/ttyS1" added
> > PPS event on source 0 at 1223337678.357389483
> > capture clear seq #1 for source 0
> > PPS clear at 70319 on source #0
> > PPS event on source 0 at 1223337679.157620784
> > capture assert seq #1 for source 0
> > PPS assert at 70519 on source #0
> > PPS event on source 0 at 1223337679.357679447
> > capture clear seq #2 for source 0
> > PPS clear at 70569 on source #0
> > PPS event on source 0 at 1223337680.157910748
> > capture assert seq #2 for source 0
> > PPS assert at 70769 on source #0
> > PPS event on source 0 at 1223337680.357969411
> > capture clear seq #3 for source 0
> > PPS clear at 70819 on source #0
> > PPS event on source 0 at 1223337681.158201551
> > capture assert seq #3 for source 0
> > PPS assert at 71019 on source #0
> > PPS event on source 0 at 1223337681.358260214
> > capture clear seq #4 for source 0
> > PPS clear at 71069 on source #0
> > PPS event on source 0 at 1223337682.158491515
> > capture assert seq #4 for source 0
> > PPS assert at 71269 on source #0
> > PPS event on source 0 at 1223337682.358550178
> > capture clear seq #5 for source 0
> > PPS clear at 71319 on source #0
> > PPS event on source 0 at 1223337683.158781479
> > capture assert seq #5 for source 0
> > PPS assert at 71519 on source #0
> > PPS event on source 0 at 1223337683.358841819
> > capture clear seq #6 for source 0
> > PPS clear at 71569 on source #0   <-------------- sleep 5 ends here
> > PPS_GETCAP: source 0
> > PPS_SETPARAMS: source 0
> > PPS_GETCAP: source 0
> > PPS_SETPARAMS: source 0
> > PPS_FETCH: source 0
> > timeout 0.000000000
> > PPS_FETCH: source 0
> > timeout 0.000000000
> > PPS_FETCH: source 0
> > timeout 0.000000000
> > PPS_FETCH: source 0
> > timeout 0.000000000
> >
> > Needless to say, after stopping and restarting ntpd works fine again...
> >
> > Ciao, Luca
>
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