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I am using an external USB sound card with a Raspberry Pi Zero W. Once in a while (up to every few minutes when playing sound) it will stop playing and /var/log/syslog logs this error:

May 21 22:52:04 music pulseaudio[14294]: [alsa-sink-USB Audio] alsa-util.c: Got POLLNVAL from ALSA
May 21 22:52:04 music pulseaudio[14294]: [alsa-sink-USB Audio] alsa-util.c: Could not recover from POLLERR|POLLNVAL|POLLHUP with snd_pcm_prepare(): No such device
May 21 22:52:04 music kernel: [175244.325496] usb 1-1: USB disconnect, device number 50
May 21 22:52:05 music pulseaudio[14294]: [alsa-sink-USB Audio] alsa-util.c: Unable to set sw params: No such device
May 21 22:52:05 music pulseaudio[14294]: [alsa-sink-USB Audio] alsa-sink.c: Failed to set software parameters: No such device
May 21 22:52:05 music kernel: [175245.275300] Indeed it is in host mode hprt0 = 00021501
May 21 22:52:06 music kernel: [175245.485152] usb 1-1: new full-speed USB device number 51 using dwc_otg
May 21 22:52:06 music kernel: [175245.485390] Indeed it is in host mode hprt0 = 00021501
May 21 22:52:06 music kernel: [175245.738077] usb 1-1: New USB device found, idVendor=1b3f, idProduct=2008, bcdDevice= 1.00
May 21 22:52:06 music kernel: [175245.738097] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
May 21 22:52:06 music kernel: [175245.738106] usb 1-1: Product: USB Audio Device
May 21 22:52:06 music kernel: [175245.738114] usb 1-1: Manufacturer: GeneralPlus
May 21 22:52:06 music kernel: [175245.768375] input: GeneralPlus USB Audio Device as /devices/platform/soc/20980000.usb/usb1/1-1/1-1:1.3/0003:1B3F:2008.0032/input/input49
May 21 22:52:06 music kernel: [175245.835815] hid-generic 0003:1B3F:2008.0032: input,hidraw0: USB HID v2.01 Device [GeneralPlus USB Audio Device] on usb-20980000.usb-1/input3

This is quite annoying as I have to restart pulseaudio every time this happens (I already have a script to scan the log for this and kill pulseaudio automatically...). Any idea what is happening here exactly (apparent the USB connection is dropped?) and how to make it more stable? I have tried two different USB sound cards and the error is the same :/

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If the USB connection is dropped across multiple sound cards, make sure the pi has a sufficient power supply. The lack of power could cause the USB sound card to shut down, and reboot due to not drawing too much power in its powered down state. A potential cause of this could be due to the resistance of long cables, or other equipment attached to the pi.

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  • I am powering the Pi Zero W from a USB port of my computer -- shouldn't that be sufficient? – fuenfundachtzig May 23 '20 at 13:35
  • I tried a USB 3 port instead of USB 2 but the problem stayed the same. – fuenfundachtzig May 24 '20 at 10:02
  • I'm not sure, as the power requirements depend on the sound card as well as the pi-0, however i have never personally had an issue powering any pi from a laptop. Do you have an official power supply you can use to test? – Jake May 26 '20 at 14:52
  • No, I don't have that option. Interestingly though, after replacing the USB cable that powers the pi by a much shorter one (0.3 m instead of 3 m), I haven't observed any more occurrences of this problem... – fuenfundachtzig Jun 9 '20 at 20:50
  • than it will be due to the resistance of the wire – Jake Jun 10 '20 at 9:17

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