[LinuxPPS] PPS/ntpd fails on fresh startup

[Rodolfo Giometti]

On Tue, Oct 14, 2008 at 10:09:40AM -0500, William S. Brasher wrote:
> On Tue, 14 Oct 2008, Rodolfo Giometti wrote:
> 
> > On Mon, Oct 13, 2008 at 03:47:23PM +0200, Luca Bertagnolio wrote:
> > > Rodolfo, when you have a minute can you comment on my issue?
> > 
> > Hi. If you wish I replay sooner, please put my e-mail address in
> > Cc. :)
> > 
> > > Why would LinuxPPS fail at the first startup, and work the second time?
> > 
> 
> 
> I have the same problem starting ntp:  it fails to start the first time 
> after booting the system.  The reason, for me, has been ppsldisc:
> 
> tara: # ppstest /dev/pps0 
> trying PPS source "/dev/pps0"
> found PPS source "/dev/pps0"
> ok, found 1 source(s), now start fetching data...
> time_pps_fetch() error -1 (Connection timed out)
> time_pps_fetch() error -1 (Connection timed out)
> ^C

This mean that LinuxPPS as registered a new source but you are getting
no IRQs from serial line. Can you please check your /proc/interrupts?

> Since it starts on the second try, I've been logging in and manually 
> running the startup script after the machine boots.  I suspect the problem 
> is somewhere in the swamp called udev and the time required for a kernel 
> process to start, but so far I haven't found a fix.

Remember that LinuxPPS doesn't configure the serial port. It just
define a PPS source and waits for IRQs from the DCD line.

Ciao,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail: giometti at enneenne.com
Linux Device Driver                          giometti at linux.it
Embedded Systems                     phone:  +39 349 2432127
UNIX programming                     skype:  rodolfo.giometti