Quectel and Telit issues

[Marc Murphy]

Hello All

Been looking at an issue on my embedded device.  Have previously been using SierraWireless MC7430 and Huawei module without issues.
I have recently changed to try a Telit 910 and a Quectel EG21-G and get :

[   47.020239] CPU: 0 PID: 427 Comm: ModemManager Not tainted 4.19.94
[   47.020285] [<c0113e18>] (unwind_backtrace) from [<c010e388>] (show_stack+0x20/0x24)
[   47.020309] [<c010e388>] (show_stack) from [<c0d20f5c>] (dump_stack+0x8c/0xa0)
[   47.020328] [<c0d20f5c>] (dump_stack) from [<c013c928>] (__warn.part.3+0xcc/0xe8)
[   47.020340] [<c013c928>] (__warn.part.3) from [<c013c9bc>] (warn_slowpath_fmt+0x78/0x94)
[   47.020355] [<c013c9bc>] (warn_slowpath_fmt) from [<c0a24e0c>] (musb_h_tx_flush_fifo+0x148/0x14c)
[   47.020370] [<c0a24e0c>] (musb_h_tx_flush_fifo) from [<c0a25dcc>] (musb_cleanup_urb+0x88/0xf0)
[   47.020383] [<c0a25dcc>] (musb_cleanup_urb) from [<c0a25fe4>] (musb_urb_dequeue+0x1b0/0x1f0)
[   47.020401] [<c0a25fe4>] (musb_urb_dequeue) from [<c09c3660>] (unlink1+0x3c/0x11c)
[   47.020415] [<c09c3660>] (unlink1) from [<c09c5a54>] (usb_hcd_unlink_urb+0x80/0xd8)
[   47.020429] [<c09c5a54>] (usb_hcd_unlink_urb) from [<c09c6fd8>] (usb_kill_urb.part.4+0x50/0xdc)
[   47.020441] [<c09c6fd8>] (usb_kill_urb.part.4) from [<c09c709c>] (usb_kill_urb+0x38/0x3c)
[   47.020477] [<c09c709c>] (usb_kill_urb) from [<bf1efd04>] (usb_wwan_close+0xcc/0xfc [usb_wwan])
[   47.020577] [<bf1efd04>] (usb_wwan_close [usb_wwan]) from [<bf199030>] (serial_port_shutdown+0x30/0x34 [usbserial])
[   47.020619] [<bf199030>] (serial_port_shutdown [usbserial]) from [<c07f7fbc>] (tty_port_shutdown+0xa0/0xa4)
[   47.020634] [<c07f7fbc>] (tty_port_shutdown) from [<c07f8834>] (tty_port_close+0x4c/0x84)
[   47.020662] [<c07f8834>] (tty_port_close) from [<bf199a0c>] (serial_close+0x34/0x5c [usbserial])
[   47.020702] [<bf199a0c>] (serial_close [usbserial]) from [<c07ee548>] (tty_release+0x100/0x60c)
[   47.020723] [<c07ee548>] (tty_release) from [<c031aa30>] (__fput+0x98/0x1e0)
[   47.020737] [<c031aa30>] (__fput) from [<c031ac08>] (____fput+0x18/0x1c)
[   47.020758] [<c031ac08>] (____fput) from [<c015e384>] (task_work_run+0xa4/0xc0)
[   47.020773] [<c015e384>] (task_work_run) from [<c010ddb0>] (do_work_pending+0xfc/0x100)
[   47.020785] [<c010ddb0>] (do_work_pending) from [<c010106c>] (slow_work_pending+0xc/0x20)
[   47.020793] Exception stack(0xec821fb0 to 0xec821ff8)
[   47.020803] 1fa0:                                     00000000 00000002 00000000 00000000
[   47.020814] 1fc0: 0000000a 004d4298 0060fa88 00000006 0000ffff b6fee968 006348e0 00000000
[   47.020824] 1fe0: 00000006 bef63a20 b6a1d461 b6a1f526 80010030 0000000a
[   47.020832] ---[ end trace 18e5006eee0b2754 ]---

It seems to happen when ModemManager is scanning the modems.  Could it be something to do with USB3 interface on the modem and timings ?  The embedded platform is only USB2.
Any update/info appreciated.

Thanks in advance

Marc