Hi JW -
--- In "jywmpg" <> wrote:
>
> Charlie
>
> Thanks very much for your well researched and very clear
description
> of the issue. I am not familiar with the driver level environment
> under Linux and greatly appreciate your insight.
Heh, neither am I, I just read & try to understand the code ..
>
> Unfortunately, try as I might, I just cannot get the TIOCMIWAIT
call
> in gpsd_ppsmonitor to complete successfully, despite the continued
> presence of the 1Hz PPS signal on the DCD line (as reported by
> statserial).
Too bad, I'm not sure what else to try. Have you tried the patched
setserial, to turn on the hardpps bit? It might be worth a try.
>
> So, at this point, I think the next move is to create the simplest
> program possible to exercise the TIOCMIWAIT call on /dev/ttyAM0
with
> the GPS plugged in, and see if it ever complete there. If it
does,
> then the problem is with the gpsd code. If it does not, then the
> problem is on the OS side. I think.
Can you try the same hardware on a desktop x86 linux machine?
There is a sample linux pps-shm clock for ntpd I found:
http://www.webchat.org/~jk/shm_linux_clock.c You could pare that
down into a small test program, w/o the shm stuff, for testing.
Once you make a small program to show TIOCMIWAIT bug that's on ARM
but not x86, you could try a post to the linux-arm ml, or
linux-arm-kernel ml. Unfortunately once you mention a 2.4 kernel,
much less a vendor's patched 2.4 kernel, the standard answer on
those lists will usually be "2.4 is too old, come back later if you
can reproduce it on a recent 2.6 kernel".
Or if your demo program _does_ work, post on the gpsd mailing list;
there seems to be a few different threads over there regarding PPS
detection already.
Good luck,
Charlie
>
>
> Thanks and Regards,
>
>
> jw
>
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