Kernel panic in dev/usb/motg.c

[Brook Milligan <brook%nmsu.edu@localhost>]

On a Beaglebone Black, I occasionally get the following kernel panic:

	panic: kernel diagnostic assertion "ep->phase == IDLE" failed: file “/NetBSD/src/sys/dev/usb/motg.c", line 1355 

Here is the traceback from the most recent:

cpu0: Begin traceback...
0xa874dbdc: netbsd:db_panic+0x14
0xa874dbfc: netbsd:vpanic+0x114
0xa874dc14: netbsd:kern_assert+0x40
0xa874dc4c: netbsd:motg_device_ctrl_start1+0x340
0xa874dc84: netbsd:usbd_transfer+0x1e4
0xa874dccc: netbsd:usbd_do_request_len+0xf0
0xa874dcec: netbsd:usbd_do_request+0x2c
0xa874dd0c: netbsd:uftdi_set+0x94
0xa874dd2c: netbsd:ucom_cleanup+0x6c
0xa874dd5c: netbsd:ucomclose+0x54
0xa874dd9c: netbsd:cdev_close+0xac
0xa874dde4: netbsd:spec_close+0x20c
0xa874de14: netbsd:VOP_CLOSE+0x44
0xa874de3c: netbsd:vn_close+0x3c
0xa874de74: netbsd:closef+0xac
0xa874ded4: netbsd:fd_close+0x124
0xa874deec: netbsd:sys_close+0x2c
0xa874dfac: netbsd:syscall+0x188
cpu0: End traceback...

This is from an unmodified kernel built from 2023-10-15 sources:

NetBSD xxx.hostname.org 10.99.10 NetBSD 10.99.10 (GENERIC) #0: Tue Oct 17 22:44:50 MDT 2023  brook%hostname.org@localhost:/NetBSD/src/2023-10-15/evbarm/obj/NetBSD/src/sys/arch/evbarm/compile/GENERIC evbarm

I would greatly appreciate ideas on how to debug this.

Thanks a lot.

Cheers,
Brook