Re: [gpsd-users] syslog error message with new version - kernel PPS failed Connection timed out

[Gary E. Miller]

Yo hans!

On Wed, 05 Aug 2015 00:01:33 +0200
hans mayer <address@hidden> wrote:

> Many thanks again for your support but I am not a step further.
> I compiled the kernel with pps debug in the hope to see more.
> 
>  > You probably do not have KPPS in you kernel
> 
> I have. Here are the modules
> bananapi:root> lsmod | grep pps
> pps_ldisc               2310  0
> pps_gpio                3357  0
> pps_core               10107  2 pps_ldisc,pps_gpio

That looks good.

> Here some syslogs:
> ( as of the fact I switched on the kernel pps debugging )
> Aug  4 23:38:47 bananapi kernel: [ 1011.465714] pps pps0: PPS event
> at 1438724326.994917747
> Aug  4 23:38:47 bananapi kernel: [ 1011.469126] pps pps0: capture
> assert seq #1001

Also good.

But you fail to mention how you enabled /dev/pps0.  Maybe you did
earlier, but my memory is short.

> and NTP also working fine with PPS/ATOM support 127.127.22.0

Using what config?

> There is till the issue that original version 3.6 doesn't generate
> syslog error messages but self compiled version 3.15 does

Which could be good, or bad...
 
> These are the messages I have:
> Aug  4 23:44:44 bananapi gpsd[2580]: gpsd:ERROR: KPPS:/dev/ttyS2
> kernel PPS failed Connection timed out
> 
> And it's not a kernal message, it comes from gpsd.

Yes, obviously.

> Why does gpsd try kernel PPS ?

Because it provids more accurate time.

> And how ?

By opening /dev/pps0

> Also /dev/ttyS2 is confusing me.
> ttyS2 is the interface where the GPS module sends the serial data.
> The 1PPS is on GPIO pin 18 - a different pin.

And your confusion is?

> I found in the documentation "build.txt" the following
> pps=yes is the default
> pps=no.  You'll lose support for updating the clock from PPS pulses.

Since gpsd is outputting the KPPS error you obviously built with pps=yes.

Which is what you want.

> What does it mean ?

It means you get zero PPS zupport.

> Which clock is not updated ?

Whichever clock you configured: SHM, or chronyd socket.

>  I don't want that gpsd updates any
> clocks.

That is sort of the hole point of PPS.  But yes, it only does that indirectly
by way of SHM and/or chronyd socket and then from ntpd or chronyd to your
system clock.

> gpsd has only one function to read the data from the gps
> module.

Yes, and the PPS also is data from the PPS.

> The 1PPS is directly managed by the ntp daemon itself.

It can be, but that is not the best way.  The best way is to have gpsd
do it.

If you are in fact telling ntpd to open /dev/pps0 then that perfectly 
explains why gpsd can not open /dev/pps0.  Read the gpsd time service
howto for the preferred configuration.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1(541)382-8588

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