Sierra Wireless em7345 disconnects from USB Bus

[Andreas Fett]

Hi,

recently we got reports from customers in the Netherlands and some parts
of Germany that their Sierra Wireless EM7345 modems (all build into
various Lenovo laptops) stopped working.

In Germany this has so far only be the case for Deutsche Telekom SIM
cards. I strongly suspect this has something to do with the network
operators infrastructure, as there are reports, that even within the
same city some locations reproducibly work and some don't.

Following hints at the Lenovo forums (for example
https://forums.lenovo.com/t5/ThinkPad-X-Series-Laptops/Sierra-Wireless-EM7345/td-p/2046489)
we upgraded the firmware which fixed these problems.

The systems in question had been working fine previously (since around
fall/winter 2015) using the same network operator, all running
ModemManager on Linux.

The symptoms in short are:
  * Modem successfully connects to APN
  * Modem disappears from USB Bus
  * Modem reappears displaying a usb product string of "1 CDC" and a
changed vendor ID.
  * After a reboot the modem is recognized by ModemManager again.

Attached are ModemManager and kernel logs for reference. They are quite
big, so I had to gzip them.

I'm still searching for a way to upgrade the firmware using Linux.

Andreas

manager/modem: path: /org/freedesktop/ModemManager1/Modem/0
manager/modem/hardware: manufacturer: 'Sierra'
manager/modem/hardware: model: 'MBIM [1199:A001]'
manager/modem/hardware: revision: 'FIH7160_V1.2_WW_01.1415.07'
manager/modem/hardware: supported: 'CAPABILITY_GSM_UMTS|CAPABILITY_LTE'
manager/modem/hardware: current: 'CAPABILITY_GSM_UMTS|CAPABILITY_LTE'
manager/modem/hardware: equipment id: '013937007228701'
manager/modem/system: device:
'/sys/devices/pci0000:00/0000:00:14.0/usb2/2-4'
manager/modem/system: drivers: 'cdc_acm, cdc_mbim'
manager/modem/system: plugin: 'Sierra'
manager/modem/system: primary port: 'cdc-wdm0'
manager/modem/system: ports: 'cdc-wdm0 (PORT_TYPE_MBIM), wwan0
(PORT_TYPE_NET), ttyACM0 (PORT_TYPE_AT)'
manager/modem/modes: supported: 'allowed: MODE_2G|MODE_3G|MODE_4G
preferred: MODE_NONE'
manager/modem/modes: current: 'allowed: MODE_2G|MODE_3G|MODE_4G
preferred: MODE_NONE'
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