I have a 9160 DK board with lte_ble_gateway on the 9160 side and hci_lpuart on the 52840 side. It works as far as being able to send and receive BLE messages but it has faults just randomly. See below:
00> ASSERTION FAIL [err == 0] @ WEST_TOPDIR/zephyr/subsys/bluetooth/host/hci_core.c:375
00>
00> k_sem_take failed with err -11
00>
00> [00:03:02.384,368] <err> os: r0/a1: 0x00000003 r1/a2: 0x20036cc8 r2/a3: 0x20022f30
00> [00:03:02.384,368] <err> os: r3/a4: 0x00000002 r12/ip: 0xa0000000 r14/lr: 0x00016543[0m
00> [00:03:02.384,368] <err> os: xpsr: 0x41000000
00> [00:03:02.384,399] <err> os: s[ 0]: 0x00000000 s[ 1]: 0x00000000 s[ 2]: 0x00000000 s[ 3]: 0x00000000
00> [00:03:02.384,399] <err> os: s[ 4]: 0x00000000 s[ 5]: 0x00000000 s[ 6]: 0x00000000 s[ 7]: 0x00000000
00> [00:03:02.384,429] <err> os: s[ 8]: 0x00000000 s[ 9]: 0x00000000 s[10]: 0x00000000 s[11]: 0x00000000
00> [00:03:02.384,429] <err> os: s[12]: 0x00000000 s[13]: 0x00000000 s[14]: 0x00000000 s[15]: 0xffffffff
00> [00:03:02.384,429] <err> os: fpscr: 0xffffffff
00> [00:03:02.384,460] <err> os: Faulting instruction address (r15/pc): 0x0001654e
00> [00:03:02.384,490] <err> os: >>> ZEPHYR FATAL ERROR 3: Kernel oops on CPU 0
00> [00:03:02.384,490] <err> os: Current thread: 0x20024a30 (unknown)
00> [00:03:02.797,149] <err> fatal_error: Resetting system
00> *** Booting Zephyr OS build v2.4.0-ncs2 ***
