Hi August,

On 06/21/2012 05:51 AM, August Mayer wrote:
> Hello,
>
> When connecting again to GPRS / PPP, after an Internet connection has
> been closed previously, the connection seems to fail. It looks like the
> ofono_modem serial data channel is completely closed when a PPP
> connection is shut down. I'm using a Telit Modem, which provides several
> serial ports, and am right now using separate serials for the AT chat
> and the data/PPP; for this reason, the AT chat continues working, but
> the data channel is dead.
>

Something similar was happening on Qualcomm based modems from Huawei, 
ZTE, etc.  The modem was sending a HUP on the PPP channel after PPP link 
was dropped.  I believe the preferred solution was to send AT&C0 when 
initializing that port.

> My question is, is it somehow necessary to re-initialise the modem data
> serial channel after a PPP connection? Or could there be a conceptual
> problem that I have overlooked?
>

This can be possible as well.  See commit 
7ed56d6844f8131cbf981e482b7bded8b20db7ab for another possible solution 
(prior to &C0) that can be used as well.

Regards,
-Denis