[LinuxPPS] pps stops when ntpd starts?

[William S. Brasher]

On Tue, 9 Jun 2009, Rodolfo Giometti wrote:

> On Tue, Jun 09, 2009 at 07:57:39AM +0200, Udo van den Heuvel wrote:
> > Hal V. Engel wrote:
> >> On Monday 08 June 2009 10:43:07 am Udo van den Heuvel wrote:
> >>> Hello,
> >>>
> >>> I cna almost reproduce with ldattch that pps works after starting
> >>> ldattch but pps stops (see /sys...) when ntpd is started?
> >>> Any others here observing the same?
> >>>
> >>> Udo
> >>
> >> I tried the 2.6.30* patch set and idattch a few weeks ago and I saw the 
> >> same thing.    I would see the time stamps when I ran ppstest after 
> >> idattch but when I ran ntpd it would stop working.  I reverted back to my 
> >> earlier setup so I don't have any idea why this was happening.
> >
> > If this is 100% reproducible for everyoen this is a blocking bug.
> > Everyone reading: Please try with ldattacha few times and then with 
> > ppsldisc. Please report your findings.
> 
> You should also enable PPS debugging messages and report them too.
> 
> Ciao,
> 
> Rodolfo
> 


I see the same problem here.  As soon as I start ntpd after running 
ldattach, ppstest begins to report timeouts, and ntpd fails to see a pps 
signal.  The serial interrupt count in /proc/interrupts continues to 
increase.

The following is from the debug log at the time I started ntpd:

Jun  9 09:12:13 tara kernel: PPS event on source 0 at 1244556733.99963157
Jun  9 09:12:13 tara kernel: capture clear seq #58 for source 0
Jun  9 09:12:13 tara kernel: PPS clear at 30813 on source #0
Jun  9 09:12:14 tara kernel: PPS event on source 0 at 1244556733.999962708
Jun  9 09:12:14 tara kernel: capture assert seq #59 for source 0
Jun  9 09:12:14 tara kernel: PPS assert at 30903 on source #0
Jun  9 09:12:14 tara kernel: PPS event on source 0 at 1244556734.99963124
Jun  9 09:12:14 tara kernel: capture clear seq #59 for source 0
Jun  9 09:12:14 tara kernel: PPS clear at 30913 on source #0
Jun  9 09:12:14 tara kernel: PPS_GETPARAMS: source 0
Jun  9 09:12:14 tara kernel: PPS_GETCAP: source 0
Jun  9 09:12:14 tara kernel: PPS_SETPARAMS: source 0
Jun  9 09:12:14 tara kernel: PPS_GETCAP: source 0
Jun  9 09:12:14 tara kernel: PPS_SETPARAMS: source 0
Jun  9 09:12:14 tara kernel: PPS_GETPARAMS: source 0
Jun  9 09:12:14 tara kernel: PPS_GETCAP: source 0
Jun  9 09:12:14 tara kernel: PPS_SETPARAMS: source 0
Jun  9 09:12:14 tara kernel: PPS_GETCAP: source 0
Jun  9 09:12:14 tara kernel: PPS_SETPARAMS: source 0
Jun  9 09:12:14 tara ntpd[2225]: ntp_io: estimated max descriptors: 1024, 
initial socket boundary: 16
Jun  9 09:12:15 tara kernel: PPS_FETCH: source 0
Jun  9 09:12:15 tara kernel: timeout 0.000000000
Jun  9 09:12:15 tara kernel: PPS_FETCH: source 0
Jun  9 09:12:15 tara kernel: timeout 0.000000000







The following is from the debug log when ntpd was started after running 
ppsldisc:

Jun  9 09:02:38 tara kernel: PPS assert at 4294940599 on source #0
Jun  9 09:02:38 tara kernel: PPS event on source 0 at 1244556158.99941231
Jun  9 09:02:38 tara kernel: capture clear seq #2 for source 0
Jun  9 09:02:38 tara kernel: PPS clear at 4294940609 on source #0
Jun  9 09:02:38 tara ntpd[2116]: ntp_io: estimated max descriptors: 1024, 
initial socket boundary: 16
Jun  9 09:02:38 tara kernel: PPS_GETPARAMS: source 0
Jun  9 09:02:38 tara kernel: PPS_GETCAP: source 0
Jun  9 09:02:38 tara kernel: PPS_SETPARAMS: source 0
Jun  9 09:02:38 tara kernel: PPS_GETCAP: source 0
Jun  9 09:02:38 tara kernel: PPS_SETPARAMS: source 0
Jun  9 09:02:38 tara kernel: PPS_GETPARAMS: source 0
Jun  9 09:02:38 tara kernel: PPS_GETCAP: source 0
Jun  9 09:02:38 tara kernel: PPS_SETPARAMS: source 0
Jun  9 09:02:38 tara kernel: PPS_GETCAP: source 0
Jun  9 09:02:38 tara kernel: PPS_SETPARAMS: source 0
Jun  9 09:02:38 tara kernel: PPS_FETCH: source 0
Jun  9 09:02:38 tara kernel: timeout 0.000000000
Jun  9 09:02:38 tara kernel: PPS_FETCH: source 0
Jun  9 09:02:38 tara kernel: timeout 0.000000000
Jun  9 09:02:39 tara kernel: PPS event on source 0 at 1244556158.999940868
Jun  9 09:02:39 tara kernel: capture assert seq #3 for source 0
Jun  9 09:02:39 tara kernel: PPS assert at 4294940699 on source #0
Jun  9 09:02:39 tara kernel: PPS event on source 0 at 1244556159.99937630
Jun  9 09:02:39 tara kernel: capture clear seq #3 for source 0
Jun  9 09:02:39 tara kernel: PPS clear at 4294940709 on source #0