changing volume kills USB audio output

[Doug Shelton]

problem happens whether changing volume using Pulseaudio, or using alsamixer from cli.

Background: USB audio device EVGA NU audio installed and working at boot
Action: change volume level (using pulseaudio or alsamixer)
Expected: volume level change, sound keeps playing
Actual result: audio output stops.

More info:
reloading alsa does not fix problem. reloading pulseaudio does not fix problem

Following lines found in syslog:
Jul 10 13:39:10 TorreyPine pulseaudio[1515]: ALSA woke us up to write new data to the device, but there was actually nothing to write.
Jul 10 13:39:10 TorreyPine pulseaudio[1515]: Most likely this is a bug in the ALSA driver 'snd_usb_audio'. Please report this issue to the ALSA developers.
Jul 10 13:39:10 TorreyPine pulseaudio[1515]: We were woken up with POLLOUT set -- however a subsequent snd_pcm_avail() returned 0 or another value < min_avail.

Release info:
Linux TorreyPine 5.11.0-22-generic #23-Ubuntu SMP Thu Jun 17 00:34:23 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

Pulseaudio package info:
Linux TorreyPine 5.11.0-22-generic #23-Ubuntu SMP Thu Jun 17 00:34:23 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

ProblemType: Bug
DistroRelease: Ubuntu 21.04
Package: pulseaudio 1:14.2-1ubuntu1.1
ProcVersionSignature: Ubuntu 5.11.0-22.23-generic 5.11.21
Uname: Linux 5.11.0-22-generic x86_64
ApportVersion: 2.20.11-0ubuntu65.1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: doug 1515 F.... pulseaudio
 /dev/snd/controlC0: doug 1515 F.... pulseaudio
CasperMD5CheckResult: unknown
CurrentDesktop: XFCE
Date: Sat Jul 10 13:48:52 2021
InstallationDate: Installed on 2020-04-26 (440 days ago)
InstallationMedia: Xubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
ProcEnviron:
 LANGUAGE=en_US
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: pulseaudio
UpgradeStatus: Upgraded to hirsute on 2021-05-08 (63 days ago)
dmi.bios.date: 03/11/2021
dmi.bios.release: 5.17
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 3002
dmi.board.asset.tag: Default string
dmi.board.name: PRIME B450-PLUS
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: Rev X.0x
dmi.chassis.asset.tag: Default string
dmi.chassis.type: 3
dmi.chassis.vendor: Default string
dmi.chassis.version: Default string
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr3002:bd03/11/2021:br5.17:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnPRIMEB450-PLUS:rvrRevX.0x:cvnDefaultstring:ct3:cvrDefaultstring:
dmi.product.family: To be filled by O.E.M.
dmi.product.name: System Product Name
dmi.product.sku: SKU
dmi.product.version: System Version
dmi.sys.vendor: System manufacturer
modified.conffile..etc.pulse.daemon.conf: [modified]
mtime.conffile..etc.pulse.daemon.conf: 2020-05-15T17:21:42.290977

[Doug Shelton (dshelton-san)]

still happens under 5.15.0-47-generic #51-Ubuntu SMP