kern/55301: rare audio panic on resume, assertion "sc->sc_pbusy == false" failed

[nia%pkgsrc.org@localhost]

>Number:         55301
>Category:       kern
>Synopsis:       rare audio panic on resume, assertion "sc->sc_pbusy == false" failed
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue May 26 07:35:00 +0000 2020
>Originator:     nia
>Release:        -current
>Organization:
>Environment:
NetBSD r 9.99.63 NetBSD 9.99.63 (R) #6: Fri May 22 23:06:42 IST 2020  nia@r:/home/nia/src/sys/arch/amd64/compile/obj/R amd64
>Description:
panic: kernel diagnostic assertion "sc->sc_pbusy == false" failed: file "/home/nia/src/sys/dev/audio/audio.c", line 5074 
cpu0: Begin traceback...
vpanic() at netbsd:vpanic+0x152
__x86_indirect_thunk_rax() at netbsd:__x86_indirect_thunk_rax
audio_pmixer_start() at netbsd:audio_pmixer_start+0x14e
audio_resume() at netbsd:audio_resume+0x138
device_pmf_driver_resume() at netbsd:device_pmf_driver_resume+0x49
pmf_device_resume_locked() at netbsd:pmf_device_resume_locked+0xd3
pmf_device_resume() at netbsd:pmf_device_resume+0x45
pmf_system_resume() at netbsd:pmf_system_resume+0xb8
acpi_enter_sleep_state() at netbsd:acpi_enter_sleep_state+0x187
sysctl_hw_acpi_sleepstate() at netbsd:sysctl_hw_acpi_sleepstate+0xdf
sysctl_dispatch() at netbsd:sysctl_dispatch+0xa5
sys___sysctl() at netbsd:sys___sysctl+0xc5
syscall() at netbsd:syscall+0x26f
--- syscall (number 202) ---
netbsd:syscall+0x26f:
cpu0: End traceback...
fatal breakpoint trap in supervisor mode
trap type 1 code 0 rip 0xffffffff8021f3d5 cs 0x8 rflags 0x202 cr2 0x7ddd6774a000 ilevel 0 rsp 0xffffd200c7c5a890
curlwp 0xfffff504491ba340 pid 14216.14216 lowest kstack 0xffffd200c7c572c0
>How-To-Repeat:

>Fix: