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: https://forum.sierrawireless.com/t/intermittent-wp7700-module-failure-fatal-error-on-the-modem/15831
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?