[alsa-devel] Can not rmmod snd_hda_codec_hdmi

[Xuebing Wang]

On Wed, 2014-12-24 at 11:57 +0200, Anssi Hannula wrote:
> 24.12.2014, 11:49, Xuebing Wang kirjoitti:
> > On Tue, 2014-12-23 at 17:21 +0100, Clemens Ladisch wrote:
> >> Xuebing Wang wrote:
> >>> rmmod: ERROR: Module snd_hda_codec_hdmi is in use
> >>
> >> rmmod snd-hda-intel first.
> >>
> > Clemens, thanks for your help.
> > 
> > I am using Fedora 21 (Ubuntu 14.04.1 has the same problem).
> > 
> > 'rmmod snd-hda-intel' shows this module is in use too. 
> > 
> > 'modinfo snd-hda-intel', nor file /lib/modules/.../modules.dep shows that any kernel modules depends
> > on snd-hda-intel or snd_hda_codec_hdmi.
> > 
> > Is it possible that a kernel thread is using these 2 modules?
> > 
> > Any ideas? Thanks.
> 
> Run this to see if some userspace process is using the ALSA devices:
> fuser -v /dev/snd/*
> 

Anssi, thanks for your help.

1) In Fedora 21 (kernel 3.17.4), 
'fuser -v /dev/snd/*' shows below:
/dev/snd/controlC0:  xbing      2400 F.... pulseaudio
/dev/snd/controlC1:  xbing      2400 F.... pulseaudio
/dev/snd/pcmC0D3p:   xbing      2400 F...m pulseaudio
/dev/snd/pcmC1D0c:   xbing      2400 F...m pulseaudio
/dev/snd/pcmC1D0p:   xbing      2400 F...m pulseaudio

After 'pulseaudio --kill' to kill pulseaudio (after disable autospawn),
lsmod shows refcount of snd_hda_intel is down from 7 to 2 as below:
$ lsmod | grep hda_intel
snd_hda_intel          30479  2

'rmmod snd_hda_intel' still shows this module is in use.

2) But, in Ubuntu 14.04.1 (kernel 3.13.0) DOES work after 'pulseaudio --kill', because lsmod shows refcount of snd_hda_intel is 5.

Any suggestions? Could it be because of kernel difference 3.17.4 vs 3.13.0?

Thanks.