Kernel Panic with WP77xx AT&T Modem Firmware

Hello All,

We have been testing with the Release 9.1 - 12 to try and find a stable solution for connecting to AT&T. Unfortunately, in all of these versions we have been having seemingly random kernel panics with the following error message:

[ 2929.635770] Fatal error on the modem.
[ 2929.638421] modem subsystem failure reason: dlcch.c:1284:Assertion (pdsch_semaphore_value <= 1) failed.
[ 2929.647938] M-Notify: General: 8
[ 2929.761040] Kernel panic - not syncing: subsys-restart: Resetting the SoC - modem crashed.
[ 2929.768329] CPU: 0 PID: 6033 Comm: kworker/0:2 Not tainted 3.18.140 #1
[ 2929.774803] Workqueue: events device_restart_work_hdlr
[ 2929.779932] [<c0014428>] (unwind_backtrace) from [<c00122ac>] (show_stack+0x10/0x14)
[ 2929.787641] [<c00122ac>] (show_stack) from [<c078b70c>] (panic+0x90/0x1f4)
[ 2929.794495] [<c078b70c>] (panic) from [<c026ae00>] (device_restart_work_hdlr+0x38/0x3c)
[ 2929.802485] [<c026ae00>] (device_restart_work_hdlr) from [<c0031174>] (process_one_work+0x1bc/0x2e0)
[ 2929.811599] [<c0031174>] (process_one_work) from [<c0031f30>] (worker_thread+0x2dc/0x3b8)
[ 2929.819754] [<c0031f30>] (worker_thread) from [<c00357dc>] (kthread+0xc8/0xd4)
[ 2929.826963] [<c00357dc>] (kthread) from [<c000e798>] (ret_from_fork+0x14/0x3c)
[ 2929.834168] cpr_panic_callback: apc_corner: [corner:7, fuse_corner:3] = 1212500 uV
[ 2929.841845] Rebooting in 5 seconds..
[ 2934.874810] Going down for restart now
[ 2934.878299] reboot: trigger wdog bite
[ 2934.881337] Causing a watchdog bite!

The issue was reported on the Sierra Wireless forums in this thread: Intermittent WP7700 module Failure: [Fatal error on the modem] - WP Series - Sierra Wireless Forum

My feeling is that it happens more often when we are transmitting data to the internet, but it can also happen randomly even when there is no data transmission at all.

Is there any further debug information that I could provide that might help tracking down the source of this issue?


hi @elliotmr,
as indicated into the topic you indicated, a new release with correction should be released once all the certification will be ready
see Intermittent WP7700 module Failure: [Fatal error on the modem] - WP Series - Sierra Wireless Forum

no need to provide additional debug information, thank you,
best regards,