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

[Azizul Hakim]

I see. So in this scenario what'll be the way to unload the driver
successfully? Is there a way to stop the mixer interface?

On Fri, Jun 12, 2015 at 2:55 AM, Takashi Iwai <tiwai at suse.de> wrote:

> At Fri, 12 Jun 2015 02:51:03 -0400,
> Azizul Hakim wrote:
> >
> > 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.
>
> /dev/snd/controlC1 is being used.  It's the mixer interface.
>
>
> Takashi
>
> >
> >
> > 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
> > >
> > [2  <text/html; UTF-8 (quoted-printable)>]
> >
>