GPRS re-connect problem

DISCUSSION August Mayer 2 participants 3 messages Jun 19, 2012 – Jun 25, 2012

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August Mayer

author

2012-06-21 10:51 UTC #0 lore raw

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.

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?

Many thanks & greetings August

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Denis Kenzior

2012-06-19 08:30 UTC #1 lore raw

Hi August,

Quoted 10 lines · August Mayer

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.

Quoted 4 lines

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

August Mayer

author

2012-06-25 08:17 UTC #2 lore raw

Hello Denis,

Wow, that was it exactly! After initialising with AT&C0, the serial data connection isn't closed anymore. Never thought that the close would originate from the modem!

Many thanks for your help & greetings August

Am 2012-06-19 10:30, schrieb Denis Kenzior:

Quoted 24 lines

Hi August,
Quoted 10 lines · August Mayer
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.
Quoted 4 lines
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?

Quoted 10 lines

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