PPS stopped once => stopped forever?

Hi all,

I am running gpsd version 3.25. My GPS is a GARMIN device connected via serial port.

I have observed that gpsd sometimes stops feeding time via SHM to ntp or chrony.

It seems to happen after gpsd got an NMEA sentence with bad checksum. After that gpsd tries to find the correct speed (38400) which often does not succeed unless gpsd is restarted. This may be a 2nd issue which I will post later.

After some time I get the message:

kernel: [T36346] pps pps0: removed

and finally:

gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout Connection timed out(110)

gpsd:PROG: KPPS:/dev/ttyS0 fd 8 cleaned up

gpsd:PROG: PPS:/dev/ttyS0 gpsd_ppsmonitor exited.

I wonder what happens here and why. Why does the kernel removes the pps0 device?

Why stops gpsd feeding the time information via SHM (even when gpsd is able to reconnect to the GPS device)?

I found a gpsd #277 ticket where Gary stated:

“Nothing can be done about restoring PPS after outages. gpsd drops root at the start, so it can't reopen the root owned SHM()'s”

What does that mean exactly? Once the connection to a GPS has been lost PPS will never work again unless gpsd is restarted?

Here are some logs around the problem. Please tell me if you need other logs or more logs.

2024-09-29T23:08:31.196614+00:00 localhost gpsd[36346]: gpsd:IO: <= GPS: $GPGGA,230831,5107.8781,N,00644.1239,E,2,27,0.53,10.36,M,45.81,M,,*4F#015

2024-09-29T23:08:31.196655+00:00 localhost gpsd[36346]: gpsd:PROG: NMEA0183: xxGGA: latch mode

2024-09-29T23:08:31.196690+00:00 localhost gpsd[36346]: gpsd:PROG: NMEA0183: GGA: hhmmss=230831 lat=51.13 lon=6.74 altMSL=10.36 mode=3 status=0

2024-09-29T23:08:31.196723+00:00 localhost gpsd[36346]: gpsd:PROG: NMEA0183: GPGGA ends a reporting cycle.

2024-09-29T23:08:31.196775+00:00 localhost gpsd[36346]: gpsd:PROG: Changed mask: {ALTITUDE|DOP|LATLON|MODE|NTPTIME|ONLINE|PACKET|REPORT|STATUS|TIME} with reliable cycle detection

2024-09-29T23:08:31.196806+00:00 localhost gpsd[36346]: gpsd:PROG: time to report a fix

2024-09-29T23:08:31.196844+00:00 localhost gpsd[36346]: gpsd:CLIENT: => client(0) len 359: {"class":"TPV","device":"/dev/ttyS0","status":2,"mode":3,"time":"2024-09-29T23:08:31.000Z","ept":0.005,"lat":51.131301667,"lon":6.735398333,"altHAE":56.1700,"altMSL":10.3600,"alt":10.3600,"track":203.9200,"magtrack":206.0900,"magvar":2.2,"speed":0.010,"climb":0.000,"geoidSep":45.810,"eph":2.518}#015#012{"class":"SKY","device":"/dev/ttyS0","hdop":0.53,"uSat":27}#015#012

2024-09-29T23:08:31.204626+00:00 localhost gpsd[36346]: gpsd:IO: <= GPS: $PGRME,1.67,M,1.29,M,2.10,M*17#015

2024-09-29T23:08:31.204662+00:00 localhost gpsd[36346]: gpsd:PROG: NMEA0183: PGRME is just after a cycle ender. ({HERR|PERR|VERR})

2024-09-29T23:08:31.204715+00:00 localhost gpsd[36346]: gpsd:PROG: Changed mask: {HERR|ONLINE|PACKET|PERR|REPORT|VERR} with reliable cycle detection

2024-09-29T23:08:31.204742+00:00 localhost gpsd[36346]: gpsd:PROG: time to report a fix

2024-09-29T23:08:31.204759+00:00 localhost gpsd[36346]: gpsd:CLIENT: => client(0) len 368: {"class":"TPV","device":"/dev/ttyS0","status":2,"mode":3,"time":"2024-09-29T23:08:31.000Z","ept":0.005,"lat":51.131301667,"lon":6.735398333,"altHAE":56.1700,"altMSL":10.3600,"alt":10.3600,"epx":2.452,"epy":2.452,"epv":2.678,"track":203.9200,"magtrack":206.0900,"magvar":2.2,"speed":0.010,"climb":0.000,"eps":4.94,"epc":5.36,"geoidSep":45.810,"eph":2.518,"sep":4.360}#015#012

2024-09-29T23:08:31.495350+00:00 localhost gpsd[36346]: gpsd:WARN: bad checksum in NMEA packet; got 4F expected 59.

2024-09-29T23:08:31.500043+00:00 localhost gpsd[36346]: gpsd:PROG: KPPS:/dev/ttyS0 assert 1727651310.999980363, sequence: 175276, clear 1727651311.499993502, sequence: 175276 - using: clear

2024-09-29T23:08:31.500094+00:00 localhost gpsd[36346]: gpsd:PROG: KPPS:/dev/ttyS0 Clear cycle: 999998, duration: 500013 @ 1727651311.499993502

2024-09-29T23:08:31.500146+00:00 localhost gpsd[36346]: gpsd:PROG: PPS:/dev/ttyS0 Clear cycle: 999998, duration: 500013 @ 1727651311.499993502

2024-09-29T23:08:31.500188+00:00 localhost gpsd[36346]: gpsd:PROG: PPS:/dev/ttyS0 Clear ignored Unknown error

2024-09-29T23:08:31.501954+00:00 localhost gpsd[36346]: gpsd:IO: SER: gpsd_next_hunt_setting(7) retries 0 diff 175258

2024-09-29T23:08:31.501998+00:00 localhost gpsd[36346]: gpsd:INFO: SER: ioctl(7, TIOCGICOUNT) rx 1923711873 tx 11177 frame 2203672 overrun 193 parity 1674 brk 215832 buf_overrun 0

2024-09-29T23:08:31.502029+00:00 localhost gpsd[36346]: gpsd:IO: SER: fd 7 set speed 57600(4097)

2024-09-29T23:08:31.702064+00:00 localhost gpsd[36346]: gpsd:INFO: SER: fd 7 current speed 57600, 8N1

2024-09-29T23:08:31.702327+00:00 localhost gpsd[36346]: gpsd:IO: SER: gpsd_next_hunt_setting(7) retries 0 diff 0

… gpsd_next_hunt_setting(7) … runs continuously

2024-09-29T23:09:34.586432+00:00 localhost gpsd[36346]: gpsd:IO: SER: gpsd_next_hunt_setting(7) retries 5359 diff 4

2024-09-29T23:09:34.586455+00:00 localhost gpsd[36346]: gpsd:INFO: SER: ioctl(7, TIOCGICOUNT) rx 1923968257 tx 11177 frame 2325729 overrun 193 parity 1674 brk 238337 buf_overrun 0

2024-09-29T23:09:34.586483+00:00 localhost gpsd[36346]: gpsd:INFO: CORE: hunt on /dev/ttyS0 failed ( 26.195375669 sec since data)

2024-09-29T23:09:34.586510+00:00 localhost gpsd[36346]: gpsd:WARN: CORE: device read of /dev/ttyS0 returned error or packet sniffer failed sync (flags {ERROR})

2024-09-29T23:09:34.586544+00:00 localhost gpsd[36346]: gpsd:CLIENT: => client(0) len 54: {"class":"DEVICE","path":"/dev/ttyS0","activated":0}#015#012

2024-09-29T23:09:34.586574+00:00 localhost gpsd[36346]: gpsd:INFO: CORE: closing /dev/ttyS0, fd 7

2024-09-29T23:09:34.586596+00:00 localhost gpsd[36346]: gpsd:IO: SER: gpsd_close(/dev/ttyS0), close(7)

2024-09-29T23:09:34.586692+00:00 localhost gpsd[36346]: gpsd:PROG: CORE: no /etc/gpsd/device-hook present, skipped running DEACTIVATE hook. No such file or directory(2)

2024-09-29T23:09:34.586727+00:00 localhost gpsd[36346]: gpsd:INFO: reconnection attempt on device 0, /dev/ttyS0

2024-09-29T23:09:34.586755+00:00 localhost gpsd[36346]: gpsd:PROG: awaken(0) fd -1, path /dev/ttyS0

2024-09-29T23:09:34.586778+00:00 localhost gpsd[36346]: gpsd:PROG: CORE: gpsd_activate(/dev/ttyS0, 2) fd -1

2024-09-29T23:09:34.586805+00:00 localhost gpsd[36346]: gpsd:PROG: CORE: no /etc/gpsd/device-hook present, skipped running ACTIVATE hook. No such file or directory(2)

2024-09-29T23:09:34.586825+00:00 localhost gpsd[36346]: gpsd:PROG: CORE: gpsd_open(/dev/ttyS0) fd -1

2024-09-29T23:09:34.586847+00:00 localhost gpsd[36346]: gpsd:PROG: SER: gpsd_serial_open(/dev/ttyS0) sourcetype 2 fd -1

2024-09-29T23:09:34.586867+00:00 localhost gpsd[36346]: gpsd:INFO: SER: opening GPS data source type 2 at '/dev/ttyS0'

2024-09-29T23:09:34.588418+00:00 localhost kernel: [T36346] pps pps0: removed

2024-09-29T23:09:34.591364+00:00 localhost gpsd[36346]: gpsd:IO: SER: fusercount: path /dev/ttyS0 fullpath /dev/ttyS0 cnt 1

2024-09-29T23:09:34.591451+00:00 localhost gpsd[36346]: gpsd:PROG: SER: fd 7 saved speed 15

2024-09-29T23:09:34.591482+00:00 localhost gpsd[36346]: gpsd:PROG: SER: fd 7 restoring fixed/saved speed 15(15)

2024-09-29T23:09:34.791306+00:00 localhost gpsd[36346]: gpsd:IO: SER: fd 7 set speed 115200(4098)

2024-09-29T23:09:37.564418+00:00 localhost gpsd[36346]: gpsd:INFO: KPPS:/dev/ttyS0 kernel PPS timeout Connection timed out(110)

2024-09-29T23:09:37.564455+00:00 localhost gpsd[36346]: gpsd:PROG: KPPS:/dev/ttyS0 fd 8 cleaned up

2024-09-29T23:09:37.564483+00:00 localhost gpsd[36346]: gpsd:PROG: PPS:/dev/ttyS0 gpsd_ppsmonitor exited.

Thanks!

Uli

From:	Wielant, Ulrich
Subject:	PPS stopped once => stopped forever?
Date:	Mon, 30 Sep 2024 08:07:43 +0000