[maemo-users] what exactly is the GPS management framework for N810?

From: Joshua Layne joshua at willowisp.net
Date: Wed Dec 12 00:20:47 EET 2007
----- Original message -----
> I am continuing to have problems with the gps functionality on my N810.
> Please note the use of "functionality" here - from everything I can tell,
> the gps hardware works fine - this looks to be a firmware/driver bug or a
> problem somewhere else in the management stack of the gps 'subsystem'
> The problem is this:
> When newly booted, the GPS works basically fine - seems to take a little
> long to get a fix, but workable.  If I then shut the GPS off (using the
> panel applet, or by closing the map application.  When I try to start the
> GPS back up, I get nothing.  A `cat /dev/pgps` gives absolutely nothing, so
> there is a problem somewhere in the stack, not with getting a fix - when
> the gps is activated and gpsd is running, /dev/pgps should ALWAYS be
> emitting some form of data.  Correct me if I'm wrong.
> `killall -HUP gpsdriver`
> and
> `killall -HUP gpsd`
> do not solve the problem.  A reboot does (although sometimes the reboot
> doesn't seem to entirely 'take' and has to be repeated)
> My understanding of the gps stack (from forums and `ps -aef|grep gps` is:
> ---
> SirfIII gps hardware
> gpsd 1.0-23 (osso branded) (/usr/sbin/gpsd -n -N -F /tmp/.gpsd_ctrl_sock
> /dev/pgp) -- I believe it is really "/dev/pgps" and is being truncated for
> some reason in ps
> gpsdriver (?proprietary? - no help available for runtime parametes) --
> (/usr/sbin/gpsdriver)
> [gpsd] -- ?what is this?  I have never seen anything like this with gpsd on
> other systems
> /usr/libexec/navicore-gpsd-helper (bundled 3rd party binary app that kick
> starts the gps unit) OR the control panel applet.
> ---
> How can I trace what is going when the gps subsystem fails?  Do I actually
> have a bad unit?  I'm past the return from where I bought it so this would
> be a warranty issue, but I really think it is a bug somewhere in the
> software stack, not a problem in the hardware.
> I would appreciate any pointers on troubleshooting this - when the GPS
> works, it is great, but it is _extremely_ frustrating to have these kind of
> issues on a $450 device.

disabling the gps (using the checkbox in the applet control) and re-enqabling it seems to kick it back to working when it fails.

I still think something is wrong either at the firmware or driver level and would be interested in helping troubleshoot it further, but I need some help on this.  I'll submit a bugreport tomorrow, as I think I finally have enough info to make it useful.

> Also, if there is (or can be made) any documentation available for how to
> programmatically interface to the gps, that would be very helpful.  I did
> not buy this unit for the built in mapping program and have no intention of
> using it - I want to be able to control the gps (including power on and
> power off) from the OS (and not using GUI applets or binary-only 3rd party
> apps).

I spoke prematurely here.  I apologize.  I just found today the information here:

and specifically, this:

which is exactly what I was looking for.

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