Modem instance reconnects automatically using EM7455

[Pradeep Gopanapalli]

Hi aleks,

Thanks for response.
Does updating firmware to latest can be of any help?

Pradeep G


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On February 7, 2023 at 03:26:01 PST, Aleksander Morgado <aleksandermj at chromium.org> wrote:
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Hey Pradeep!

> We am seeing a strange issue where Modem instance reconnects automatically once
> in a while, modem used in EM7455. This happens after some time of succesful
> data connection and the once the issue occurs network is disrupted for 30-45 seconds.
> This is very random and some times happens quite often like every 1 hour or so.
> From the debug logs I can see there is USB disconnect and qcdm reports "unexpected port hangup" .
> I tried searching modemforums and issues in gitlab, but didn't find any one reporting this kind
> of behavior for EM7455, it would be of great help if anyone can throw some light on this failure.
>
> Logs:
> From logs:
> 2023-02-03T16:56:13.564 INFO   kern   kernel:[16332.259560] usb 1-1.3: USB disconnect, device number 5
> 2023-02-03T16:56:13.044 DEBUG  daemon ModemManager[5106]: <debug> [modem0/ttyUSB0/qcdm] unexpected port hangup!
> 2023-02-03T16:56:13.044 DEBUG  daemon ModemManager[5106]: <debug> [modem0/ttyUSB0/qcdm] forced to close port
> 2023-02-03T16:56:13.044 DEBUG  daemon ModemManager[5106]: <debug> [modem0/ttyUSB0/qcdm] device open count is 0 (close)
> 2023-02-03T16:56:13.044 DEBUG  daemon ModemManager[5106]: <debug> [modem0/ttyUSB0/qcdm] closing serial port
> 2023-02-03T16:56:13.044 DEBUG  daemon ModemManager[5106]: <debug> [modem0/ttyUSB0/qcdm] serial port closed
> 2023-02-03T16:56:13.565 INFO   kern   kernel:[16332.261131] qcserial ttyUSB0: Qualcomm USB modem converter now disconnected from ttyUSB0
> 2023-02-03T16:56:13.566 INFO   kern   kernel:[16332.261629] qcserial 1-1.3:1.0: device disconnected
> 2023-02-03T16:56:13.567 INFO   kern   kernel:[16332.262427] qcserial ttyUSB1: Qualcomm USB modem converter now disconnected from ttyUSB1
> 2023-02-03T16:56:13.567 INFO   kern   kernel:[16332.262472] qcserial 1-1.3:1.2: device disconnected
> 2023-02-03T16:56:13.047 DEBUG  daemon ModemManager[5106]: <debug> [modem0/ttyUSB2/at] unexpected port hangup!
> 2023-02-03T16:56:13.047 DEBUG  daemon ModemManager[5106]: <debug> [modem0/ttyUSB2/at] forced to close port
> 2023-02-03T16:56:13.047 DEBUG  daemon ModemManager[5106]: <debug> [modem0/ttyUSB2/at] device open count is 0 (close)
> 2023-02-03T16:56:13.047 DEBUG  daemon ModemManager[5106]: <debug> [modem0/ttyUSB2/at] closing serial port...
> 2023-02-03T16:56:13.047 DEBUG  daemon ModemManager[5106]: <debug> [modem0/ttyUSB2/at] serial port closed
> 2023-02-03T16:56:13.569 INFO   kern   kernel:[16332.264374] qcserial ttyUSB2: Qualcomm USB modem converter now disconnected from ttyUSB2
> 2023-02-03T16:56:13.569 INFO   kern   kernel:[16332.264424] qcserial 1-1.3:1.3: device disconnected                                  2023-02-03T16:56:13.572 INFO   kern   kernel:[16332.267600] qmi_wwan 1-1.3:1.8 wwan0: unregister 'qmi_wwan' usb-0000:00:16.0-1.3, WWAN/QMI device
> 2023-02-03T16:56:13.053 NOTICE daemon netifd: Network device 'wwan0' link is down
>
>
> Versions used
> libqmi: 1.28.6-1
> libmbim: 1.24.8-1
> modemmanager: 1.16.6.1
> openwrt: 19.07 based solution.
>
> Carrier : Vodafone
> EM7455 firmware used: "SWI9X30C_02.24.03.00 r6978 CARMD-EV-FRMWR2 2017/03/02 13:36:45
> response: '!IMPREF: ^M
>  preferred fw version:    02.24.03.00^M
>  preferred carrier name:  VODAFONE^M
>  preferred config name:   VODAFONE_001.001_000^M
>  current fw version:      02.24.03.00^M
>  current carrier name:    VODAFONE^M
>  current config name:     VODAFONE_001.001_000'
>

This is a modem firmware crash; we see the device going away from the
USB bus and then back again after it self-resets. There is absolutely
nothing we can do to prevent this (unless you detect this is happening
due to certain configuration or something).

If you can more or less reliably reproduce this in a controlled dev
environment, you could try to gather QXDM traces from the modem and
talk to Sierra so that they have them analyzed. You should definitely
involve the manufacturer in troubleshooting this.

--
Aleksander

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