[alsa-devel] Question about struct snd_soc_dai() :: cpu_dai->codec

[Takashi Iwai]

On Wed, 27 Jul 2016 20:04:56 +0200,
Mark Brown wrote:
> 
> On Wed, Jul 27, 2016 at 10:51:26PM +0530, Vinod Koul wrote:
> > On Wed, Jul 27, 2016 at 07:57:05AM +0200, Takashi Iwai wrote:
> 
> > > For unloading the module, yes, it should have been prevented by
> > > managing the module refcount.  However, unbinding can't be stopped by
> > > that.  It's a known problem.
> 
> > Oh yes, unload is an issue. Are these any solutions to prevent this?
> 
> > In core, should we de-register the card if one of the components exits. The
> > .remove should be called for the driver, thus triggering unregister?
> 
> That's the theory but it's full of holes at the minute.  Someone needs
> to sit down and fix all the holes in there.

Yeah, and it's not so trivial.  The unbind can be called at any time,
even during a stream is running.  This is a kind of hot unplug.  The
whole nightmare we've faced with usb-audio and co will strike again.

I'm wondering whether it's a better option to block the unbind
behavior, either in driver base (allowing to return an error) or in
the sound side (waiting in remove() until the sane point). 


Takashi