Sierra Wireless EM7345 ThinkPad 8 and 10 general issues

Question

This was posted as a reply to german forum but it was deleted Symptoms (mobile connection is connected)
 1. mobile connection randomly disconnects. It is possible to reconnect again. 2. when resume from Connected standby mode the mobile connection appears to be connected but it is dead. It is not possible to disconnect nor turn off the mobile connection, it is stuck. Windows restart is required to resolve it. 3. when resume from Connected standby mode the EM7345 composite device disappears at all from Device Manager and new unknown device '1 CDC' appears. Windows restart is required to resolve it. Note: Issues 2 and 3 occurs when running on battery only. I don't have any occurence when the tablet was plugged in AC, turned off (into Connected standby mode) and on, yet. I have already tried to reinstall the 1.6.10513.4153 driver, no luck. I have also tried to disable 'USB selective suspend' feature in driver settings and switch off GNSS device (because it has Sierra Wireless driver), no change. I have latest BIOS 1.24 (ThinkPad 8, 64 bit). It is hard to reproduce the case 3 but I have almost reliable steps: 1. uninstall current driver (even it is the latest version)2. restart3. install current 1.6.10513.4153 driver, select Custom Setup, make sure the 'WWAN Logging Tool' is selected, finish the installation4. restart 5. establish mobile connection6. go to Start menu, Intel group, start 'M.2 WWAN Logging Tool'7. press Start Trace button8. turn off the tablet (while the tracing is running) by power button, wait for a minute 9. turn on the tablet(repeat steps 8 and 9 multiple times, in case you can not reproduce it at the first time) EM7345 device disappears with typical unknown 1 CDC device. Yes, it is not a standard operation but it is easily reproducible with the same result. Similar issue is reported in other forum posts for ThinkPad 8 and 10
 http://forums.lenovo.com/t5/ThinkPad-Tablets/Thinkpad-8-with-Sierra-Wireless-EM7345-Driver-or-Firmware-issue/m-p/1758961http://forums.lenovo.com/t5/ThinkPad-Slate-Tablets/Tablet-8-win-8-1-unbekanntes-Gerät-1-CDC-kein-mobiles-breitband/m-p/1839400http://forums.lenovo.com/t5/ThinkPad-Tablets/Thinkpad-10-EM7345-stops-working/td-p/1742115http://forums.lenovo.com/t5/ThinkPad-Tablets/Flaky-WWAN-in-ThinkPad-10/m-p/1793007 Additional related issue - firmware update does not work
 Old firmware 1.1 that can not be updated to 1.2, read this thread http://forums.lenovo.com/t5/T400-T500-and-newer-T-series/T540p-Sierra-WWAN-EM7345-reliability/m-p/1839271#M106663 The 1.2 firmware might help to resolve the issue (although this post states it actually did not help). Technical details When the USB composite device (EM7345 = WWAN + GNSS) disappears it incorrectly identifies itself as VID = 1519, PID = F000 so Windows can not find proper driver for the device and displays it with (?) icon. If you remove the '1 CDC' device from Device Manager and perform 'Scan for hardware changes' this time it is correctly identified as VID = 1199, PID = A001 and installed (these tasks can be automated using devcon.exe command-line tool, so the fix wouldn't require OS restart everytime it occurs. It is still hack, not a solution). It looks like a firmware bug because the USB composite device and WWAN MBIM device uses Microsoft generic driver. Summary Given the price tag of ThinkPad 8 and 10 tablets, Lenovo should fix that because this is basic functionality failure. Disappearing WWAN device that needs full restart is really serious issue. And again, please diagnose and resolve the issue (hint , hint) instead of "try to reinstall this, try to reinstall that, replace this, replace that" advices. It leads to nowhere because the driver/firmware is buggy as it was in the past with Ericsson device. (copy of the post is stored)

Answer 1

More details. I installed USB Device Viewer from Windows Driver Kit to get some information. When the EM7435 device is healthy: [Port3] : USB Composite Device
Is Port User Connectable: no
Is Port Debug Capable: no
Companion Port Number: 0
Companion Hub Symbolic Link Name:
Protocols Supported:
USB 1.1: yes
USB 2.0: yes
USB 3.0: no
Device Power State: PowerDeviceD2
---===>Device Information<===---
String Descriptor for index 2 not available while device is in low power state.
ConnectionStatus:
Current Config Value: 0x01 -> Device Bus Speed: High (is not SuperSpeed or higher capable)
Device Address: 0x05
Open Pipes: 6
===>Device Descriptor<===
bLength: 0x12
bDescriptorType: 0x01
bcdUSB: 0x0200
bDeviceClass: 0xEF -> This is a Multi-interface Function Code Device
bDeviceSubClass: 0x02 -> This is the Common Class Sub Class
bDeviceProtocol: 0x01 -> This is the Interface Association Descriptor protocol
bMaxPacketSize0: 0x40 = (64) Bytes
idVendor: 0x1199 = Sierra Wireless Inc.
idProduct: 0xA001
bcdDevice: 0x1729When the EM7435 device disappears and is shown as unknown '1 CDC' device [Port3]
Is Port User Connectable: no
Is Port Debug Capable: no
Companion Port Number: 0
Companion Hub Symbolic Link Name:
Protocols Supported:
USB 1.1: yes
USB 2.0: yes
USB 3.0: no
---===>Device Information<===---
String Descriptor for index 2 not available while device is in low power state.
ConnectionStatus:
Current Config Value: 0x00 -> Device Bus Speed: High (is not SuperSpeed or higher capable)
Device Address: 0x02
Open Pipes: 0
*!*ERROR: No open pipes!
===>Device Descriptor<===
bLength: 0x12
bDescriptorType: 0x01
bcdUSB: 0x0200
bDeviceClass: 0x02 -> This is a Communication Device
bDeviceSubClass: 0x00
bDeviceProtocol: 0x00
bMaxPacketSize0: 0x40 = (64) Bytes
idVendor: 0x1519 = Comneon GmbH Co., Ohg.
idProduct: 0xF000
bcdDevice: 0x1234 I have also tried to diagnose what exactly happens after returning from Connected standby usingUSB hardware verifier but as usually I can not reproduce it while the tool is used