kern/54177: playing audio in firefox doesn't work after kernel update

[coypu%sdf.org@localhost]

>Number:         54177
>Category:       kern
>Synopsis:       playing audio in firefox doesn't work after kernel update
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed May 08 16:00:00 +0000 2019
>Originator:     coypu
>Release:        NetBSD 8.99.39
>Organization:
>Environment:
NetBSD plu 8.99.39 NetBSD 8.99.39 (GENERIC) #3: Wed May  8 18:34:58 IDT 2019  fly@plu:/home/fly/obj3/sys/arch/amd64/compile/GENERIC amd64

>Description:
audio in cmus/mpv: works good
audio in firefox: broken. sometimes it will play a few seconds fine though.
either playing a local file or youtube.

using:
[     1.051947] hdaudio0 at pci0 dev 31 function 3: HD Audio Controller
[     1.051947] hdaudio0: interrupting at msi4 vec 0
[     1.051947] hdafg0 at hdaudio0: vendor 10ec product 0298
[     1.051947] hdafg0: DAC00 2ch: Speaker [Built-In]
[     1.051947] hdafg0: DAC01 2ch: HP Out [Jack]
[     1.051947] hdafg0: ADC02 2ch: Mic In [Built-In]
[     1.051947] hdafg0: 2ch/2ch 44100Hz 48000Hz PCM16 PCM20 PCM24
[     1.051947] audio0 at hdafg0: full duplex, playback, capture, mmap, independent
[     1.051947] audio0: slinear_le:16 2ch 48000Hz, blk 40ms for playback
[     1.051947] audio0: slinear_le:16 2ch 48000Hz, blk 40ms for recording
[     1.051947] spkr0 at audio0: PC Speaker (synthesized)
[     1.051947] wsbell at spkr0 not configured
[     1.051947] hdafg1 at hdaudio0: vendor 8086 product 2809
[     1.051947] hdafg1: DP00 8ch: Digital Out [Jack]
[     1.051947] hdafg1: 8ch/0ch 48000Hz PCM16*

>How-To-Repeat:

>Fix: