[gpsd-users] How to reset ttyUSB0 baud rates automatically between system resume?

[Chen Wei]

I have a Holux M-241 connected by USB cable. Between system suspend and resume,
sometimes the gpsd stop working. The GPS has locked to satellites and gpsd
daemon is still running, but client can't retrieve info from gpsd. It appears
the baud rates of /dev/ttyUSB0 changed from 38400 to 115200 after resume, that
might cause gpsd fail to probe. When run 

gpsd -N -n -D5 /dev/ttyUSB0

gpsd only try probe 3 drivers,

gpsd:PROG: Probing "Garmin USB binary" driver...
...
gpsd:PROG: Probe not found "Garmin USB binary" driver...
...
gpsd:PROG: Probing "GeoStar binary" driver...
...
gpsd:PROG: Probe not found "GeoStar binary" driver...
...
gpsd:PROG: Probing "Trimble TSIP" driver...
...
gpsd:PROG: Probe not found "Trimble TSIP" driver...
...
gpsd:PROG: no probe matched...


If reset the baud rate to 38400 manually, then gpsd can correctly probe this GPS

gpsd:PROG: => Probing for MediaTek
gpsd:IO: => GPS: $PMTK605*31\x0d\x0a
gpsd:IO: <= GPS: $PMTK001,-1,0*1F
gpsd:WARN: unknown sentence: "$PMTK001,-1,0*1F\x0d\x0a"
gpsd:DATA: packet from /dev/ttyUSB0 with {ONLINE|PACKET}
gpsd:IO: <= GPS: $PMTK001,-1,0*1F
gpsd:WARN: unknown sentence: "$PMTK001,-1,0*1F\x0d\x0a"
gpsd:DATA: packet from /dev/ttyUSB0 with {ONLINE|PACKET}
gpsd:IO: <= GPS: $PMTK001,-1,0*1F
gpsd:WARN: unknown sentence: "$PMTK001,-1,0*1F\x0d\x0a"
gpsd:DATA: packet from /dev/ttyUSB0 with {ONLINE|PACKET}
gpsd:IO: <= GPS: $PMTK001,-1,0*1F
gpsd:WARN: unknown sentence: "$PMTK001,-1,0*1F\x0d\x0a"
gpsd:DATA: packet from /dev/ttyUSB0 with {ONLINE|PACKET}
gpsd:IO: <= GPS: $PMTK001,-1,0*1F
gpsd:WARN: unknown sentence: "$PMTK001,-1,0*1F\x0d\x0a"
gpsd:DATA: packet from /dev/ttyUSB0 with {ONLINE|PACKET}
gpsd:IO: <= GPS: $PMTK705,B-core_1.20,0043,01017-00F,1.0*72
gpsd:WARN: unknown sentence: 
"$PMTK705,B-core_1.20,0043,01017-00F,1.0*72\x0d\x0a"
gpsd:PROG: found trigger string $PMTK705,.
gpsd:PROG: switch_driver(MTK-3301) called...
...

The Holux M-241 uses cp210x converter driver,

ls -l /dev/serial/by-id/
total 0 lrwxrwxrwx 1 root root 13 Aug 13 07:04
usb-Silicon_Labs_CP2102_USB_to_UART_Bridge_Controller_0001-if00-port0 ->
../../ttyUSB0

Is it possible to reset its baud rates automatically between system resume? or
keeps the system from changing the baud rates?


-- 
Chen Wei