[alsa-devel] Can't Unload ALSA Driver Without Disconnecting the Device

[Azizul Hakim]

I tried that command. The output is as below:

                                    USER        PID ACCESS COMMAND
/dev/snd/controlC0:  mhaki005   2043 F.... pulseaudio
/dev/snd/controlC1:  mhaki005   2043 F.... pulseaudio
/dev/snd/pcmC0D0c:   mhaki005   2043 F...m pulseaudio


I think pcmC0D0c stands for "Capture" device. My device is a playback
device. So I don't think it is being used by anyone.


On Fri, Jun 12, 2015 at 2:41 AM, Takashi Iwai <tiwai at suse.de> wrote:

> At Fri, 12 Jun 2015 02:28:16 -0400,
> Azizul Hakim wrote:
> >
> > Hi,
> >
> > I've been developing a sound card driver for a USB device using ALSA. My
> > driver is almost working but I've got one small issue. If I try to unload
> > the driver module using "rmmod" command  when the device is still
> connected
> > to the USB port, it says "Module is in use" even though I'm not playing
> any
> > sound files or anything.
> >
> >
> > If I try to execute the "lsmod" command I see that it is saying the usage
> > count of my driver to be 1, but it doesn't say anything about who is
> using
> > it. Once I disconnect the device from the USB port, I can easily unload
> the
> > module.
> >
> >
> > So it seems to me it won't be possible to unload a sound card driver if
> the
> > card is attached in the computer. Is my assumption correct? If not, what
> > might be some key points to solve the issue?
>
> Check "fuser -v /dev/snd/*" as root.  Something (e.g. a mixer
> application or sound backend) must be accessing the device.
>
>
> Takashi
>