Arch Linux

karna

Member

Registered: 2015-02-02

Posts: 25

alsa sound disappears few days after boot

I am using a USB audio DAC on my Lenovo T440s arch linux machine. When I am not listening to audio, I remove the USB audio DAC, and plug it in when I need audio. This works most of the time, but after a few days (say 4 days), I can not get any audio from my computer. It seems that alsa can not see the device from my user id. It can find the device  as superuser though:

$ amixer
amixer: Mixer attach default error: No such file or directory
$ sudo amixer
Simple mixer control 'PCM',0
  Capabilities: pvolume pswitch pswitch-joined
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 128
  Mono:
  Front Left: Playback 128 [100%] [0.00dB] [on]
  Front Right: Playback 128 [100%] [0.00dB] [on]

Output from aplay -l :

$ aplay -l
aplay: device_list:270: no soundcards found...
$ sudo aplay -l
[sudo] password for mohits: 
**** List of PLAYBACK Hardware Devices ****

Please note  sudo aplay -l  hangs. I could not abort it with CTRL-C

Any ideas?

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 21,720

Re: alsa sound disappears few days after boot

Use

sudo fuser -v /dev/snd/*

to see which devices are accessed and potentially blocked by any given application, look through dmesg for any errors, make sure nothing is potentially still playing on the device if you unplug it, maybe there is a problem with the device node suddenly disappearing while still being used by applications. If you use TLP or similar, try to disable USB powersaving/autosuspend that might be activated, these can often lead to strange issues.

Last edited by V1del (2017-02-09 07:47:04)

karna

Member

Registered: 2015-02-02

Posts: 25

Re: alsa sound disappears few days after boot

Thanks for your suggestions. I will have to wait for a few days to try them. I recently rebooted my machine to get audio back. The dmesg only gives the messages after current boot, correct? Is there a way to read log from before the current boot-up?

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 21,720

Re: alsa sound disappears few days after boot

Yes the journal keeps all logs, you can use

journalctl -b-1

for the boot prior to your current one (and -2 -3 -4 and so fort...)

karna

Member

Registered: 2015-02-02

Posts: 25

Re: alsa sound disappears few days after boot

Thanks!