Intermittent WP7700 module Failure: [Fatal error on the modem]


I am experiencing intermittent Modem Failures on my MangOH red.
I have not encountered this until “app start redSensorToCloud” at which point it appears to be happening with regularity.

Fatal error on the modem.
[ 47.491506] modem subsystem failure reason: dlcch.c:1284:Assertion (pdsch_semaphore_value <= 1) failed.
[ 47.500967] M-Notify: General: 8
[ 47.610151] Kernel panic - not syncing: subsys-restart: Resetting the SoC - modem crashed.

On Friday this Fault followed by the subsequent reboot of the WP7700 occurred at perhaps 2-5minute intervals.

root@swi-mdm9x28-wp:~# cm radio
Power: ON
Current Network Operator: AT&T
Current RAT: LTE network (LE_MRC_RAT_LTE)
Status: Registered, home network (LE_MRC_REG_HOME)
Signal: Weak signal strength (2) //varies between 2 and 5
PS: Packet Switched Registered, home network (LE_MRC_REG_HOME)

root@swi-mdm9x28-wp:~# cm info
Device: WP7700
IMEI: 353805090108080
FSN: W8810385110310
Firmware Version: SWI9X06Y_02.16.06.00 7605a6 jenkins 2018/06/20 17:56:12
Bootloader Version: SWI9X06Y_02.16.06.00 7605a6 jenkins 2018/06/20 17:56:12
MCU Version: 002.009
PRI Part Number (PN): 9908049
PRI Revision: 001.002
Carrier PRI Name: ATT
Carrier PRI Revision: 001.026_000
SKU: 1103736
Last Reset Cause: Crash
Resets Count: Expected: 47 Unexpected: 71

Oddly enough this morning I have been running w/o MODEM FAULT for 20mins straight w/o Modem failure & reboot!!!

I have freshly built the latest most recent versions, here are some general details:

root@swi-mdm9x28-wp:~# cm sim info
ICCID: 89011703278211571180
Home Network Operator: AT&T
IMSI: 310170821157118
Phone Number:

I am seeing streaming NACK msgs on the console port:
[ 4235.851390] i2c-msm-v2 78b8000.i2c: NACK: slave not responding, ensure its powered: msgs(n:1 cur:0 tx) bc(rx:0 tx:14) mode:FIFO slv_addr:0x3a MSTR_STS:0x0c1300c8 OPER:0x00000090
[ 4236.850666] i2c-msm-v2 78b8000.i2c: NACK: slave not responding, ensure its powered: msgs(n:1 cur:0 tx) bc(rx:0 tx:14) mode:FIFO slv_addr:0x3a MSTR_STS:0x0c1300c8 OPER:0x00000090

Is there a possible issue with being logged in on the console port as well as the CF3 Module port (ssh@root…)?
Is there an issue with USB connectivity/interaction to the Host PC that is resulting in Critical Modem Faults? (I am building/running on an Ubuntu 16.04 VM on a Win10 system, the VM has 4 CPU’s & 6GB RAM).

Has anyone encountered similar critical Modem Faults and isolated the root cause?

Is there a simple process to initiate redSensorToCloud app auto start on boot as further diagnosis/isolation and to eliminate any host-USB interactions?

Appreciate any similar/related experiences anyone has had!!

UPDATE: After 18 minutes of uninterrupted operation (a record) - the Modem Crapped. 2 faults+reboots then when up I restarted the redSensorToCloud app and the Modem immediately Failed two more times (4 in total - from the 71 Unexpected Resets to 75).
At this point I was able to get one data transfer to AirVantage and the Modem failed & rebooted again! …and despite app start or not the Modem is now back to rebooting at a high periodic rate.

A heat issue? - doubtful as the modem module is reporting 36deg C…

Further update: it runs longer without redSensorToCloud running. Starting the app spurs almost immediate modem FAULT and reboot.

Thanks all,



do you see the reset when you download a fresh firmware to the unit? no mangoh red specific software that is



Thanks for hte suggestion - precisely what I planned for 1st thing this morning - get a baseline.

I’ve reflashed the modem firmware (ATT v9.1) - with no change.
I’m not quite clear on a baseline build to load - or if the Recovery Procedure is what you imply.
(incidentally per Shib’s recommendation I have built with the latest Legato 18.10.3).

Appreciate any clarity/pointers,



Hi Mike,

Just linking the two posts, in case anyone can use the response posted in the general WP forum:




Hi Ryan,

do you have any info about whether release 11 will support SFTP?

With the other WP modems, rebuilding yocto with curl --with-libssh2 enables SFTP, but this doesn’t work with the WP7700.



Hi! I am new to this forum and was looking for the same issue online source, stumbled here. Definitely following this forum. I know for a fact that WP7700 doesn’t work with this.