[LinuxPPS] PPS stops working after a few seconds

[Hal V. Engel]

On Thursday 26 March 2009 10:33:22 am Udo van den Heuvel wrote:
> clemens at dwf.com wrote:
> > Join the club.
>
> Which one? ;-)
>
> > This is another instance of the problem that Hal V. Engel and I discussed
> > about a month ago.  I have seen it (mainly) on startup, and Hal's
> > suggestion to start ntpd, stop it, then restart it, works.  It would be
> > nice to know what the problem is with linuxPPS that this works around,
> > but it does consistantly start for me now.
> >
> > You dont say if this is just after a reboot (and you never had ntpd
> > running) or if it just 'happened', but from the counts it looks like the
> > latter.
>
> It happened.
> ntpd was running for a few weeks on my trusty VIA EK8000.
>
> > I have seen this same behaviour of the counts increasing by one each time
> > I do something, and assume that it should be a clue as to what is wrong
> > with the code.
> >
> > So, no solution, but welcome to the club.
>
> No solution?
>
> > [[ As I mentioned above, Hal's suggestion of starting ntpd (from init.d)
> > waiting 20sec, killing ntpd, then restarting ntpd works for me. ]]
>
> Ah, a workaround...!
> Will try!

My current solution involves a wrapper init script that starts ppsldisc and 
then ntpd (by calling the normal ntp init script - /etc/init.d/ntpd start) and 
then killing both and then restarting these a second time.  I have my custom 
wrapper script (/etc/init.d/ntp-pps) setup as a startup script for the default 
run level.   I have attached a copy of my wrapper script as an example since 
it will likely need to be modified for your distro and how things are setup on 
your machine.  

Using this wrapper script makes the ntp startup 100% reliable after restarting 
my system.  But if I only start ppsldisc and ntpd once after a system restart 
it always fails.   This workaround is a hack and it would be nice if the 
underlaying issue was fixed. 

Hal
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#!/sbin/runscript
depend() {
        need net
        use dns logger
        after  ntp-client
}

start() {

        ebegin "Starting custom ntpd"

        /bin/ppsldisc /dev/ttyS1 &
        sleep 5 # give ppsldisc and udev time to get settled

        /etc/init.d/ntpd start

        sleep 20 # give ntpd time to start before killing ppsldisc
        killall ppsldisc
        /etc/init.d/ntpd stop

        /bin/ppsldisc /dev/ttyS1 &
        sleep 5
        /etc/init.d/ntpd start
        sleep 50 # give ntpd time to start before killing ppsldisc

        killall ppsldisc
}

stop() {
        ebegin "Stopping custom ntpd"
        /etc/init.d/ntpd stop
}