Re: [alsa-devel] [RFC][PATCH] ASoC: soc-core: verify Sound Card normality

[Takashi Iwai <tiwai@suse.de>]

On Thu, 30 Mar 2017 23:53:34 +0200,
Mark Brown wrote:
> 
> On Wed, Mar 29, 2017 at 02:45:37AM +0000, Kuninori Morimoto wrote:
> 
> > To avoid Sound Card crash in (2) case, what we can do now is, add dirty
> > flag on Sound Card, and avoid to open Sound Card.
> > This patch solved this issue.
> 
> I think this is a good direction to at least start to mitigate these
> problems (which we really should be doing) and hopefully make it easier
> to do further improvements in future.  There's obviously more places
> where we should be checking the flag (controls for example) but they can
> be added later.  One thing I would like to see is instead of setting the
> flag directly when we see a problem call a function to do it.  That way
> if we want to improve things in the future we can do that without having
> to update the callers again.

BTW, ALSA core has snd_card_disconnect() that does this kind of
shut-up from user-space.  It was introduced for hot-unplug, but
basically unbinding is the software hot-unplug.  So, if ASoC won't
rebind a once-unbound component, you can simply call
snd_card_disconnect() at the component unbinding time to assure that
no further user actions can be done.


Takashi