Re: MM 0.6.0 conflicts with USB GPS device?

[Dan Williams <dcbw redhat com>]

On Fri, 2013-05-31 at 17:57 +0200, W. Martin Borgert wrote:
> Hi,
>
> ModemManager 0.6.0 (02ddf9a6732fba19c248d83cadfb56452c815091) seems to  
> be confused, when a USB GPS device is connected.
> The GPS device always sends permanently data in form of ASCII strings at
> 4800 bps.
> It does not answer to any commands, such as ATI.
> Unfortunately it idenfies itself as a USB serial adaptor, so ModemManager
> rightly tries to find a modem there.

Unfortunate :(

> But ModemManager should detect, that this is not a modem and let the device
> alone.
> Instead it tries to identify the poor device again and again, which
> prevents the legitimate GPS software to access it.

When you say "again and again", what do you mean?  ModemManager sends a
sequence of AT commands like AT+GCAP, ATI, etc, then moves on to binary
QCDM commands, and if all of these fail, it will stop and leave the
device alone.  That can take 10 or so seconds though.

> The GPS device as shown by lsub:
>
> ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port
>
> The output from MM:
>
> modem-manager.debug[1577]: <debug> [1370004683.185636]  
> [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '\0'
> modem-manager.debug[1577]: <debug> [1370004683.189633]  
> [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '\0'
> modem-manager.debug[1577]: <debug> [1370004683.214500]  
> [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '\0\0'
> modem-manager.debug[1577]: <debug> [1370004683.217178]  
> [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): --> 'AT+GCAP<CR>'
> modem-manager.debug[1577]: <debug> [1370004683.919845]  
> [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '\0\0\0\0\0\0\0'
> modem-manager.debug[1577]: <debug> [1370004683.945792]  
> [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '\0'
> modem-manager.debug[1577]: <debug> [1370004683.986895]  
> [mm-at-serial-port.c:334] debug_log(): (ttyUSB0): <-- '\0'
>
> Does somebody have an idea how to solve the problem?

This looks normal, how long does the process go on before ModemManager
stops talking to the device?

Dan