[LinuxPPS] refclock_nmea patch

[Udo van den Heuvel]

Rodolfo Giometti wrote:
> On Tue, Oct 23, 2007 at 06:26:53PM +0200, Udo van den Heuvel wrote:
>> I see in the LinuxPPS source that a port is checked: First we check if
>> current device is a PPS valid PPS one.
>> What is the use? (if this test fails on my /dev/gps0?)
> 
> Just to verify that the supplied device is a PPS source. It fails
> because your /dev/gps0 is a serial line and _not_ a PPS source.

But how does LinuxPPS which /dev/pps* to create for which serial ports?
Only during the startup phase we use setserial to enable hardpps etc.

>> So what use is it then to make /dev/gps0 if we have an automagic /dev/pps0?
> 
> Beacuse /dev/pps0 is _only_ a PPS source so you cannot get GPS/NMEA
> data from it. That's why you need both /dev/gps0 and /dev/pps0.  The
> former is used to collect GPS/NMEA data while the latter is is used to
> collect PPS data.
> 
>> (just trying to understand)
> 
> Hope I was clear now. :)
> 
> Does your code work now? :D

The code works/worked. Only the logging is/was unclear, combined with
the different functioning of LinuxPPS.

> There is nothing strange since in LinuxPPS a PPS source _cannot_ be
> also a GPS data source.
>
> This was the trick which allows us to be RFC compliant! ;)

But it was (also?) about being able to address devices that do not
appear as files in the system?
What item of the RFC prohibits the re-use of a fd for GPS/PPS?

Udo