[alsa-devel] [PATCH v3 1/2] ALSA: Added jack detection KControl support

[Takashi Iwai]

At Fri, 9 Aug 2013 17:39:47 +0100,
Mark Brown wrote:
> 
> On Fri, Aug 09, 2013 at 03:52:04PM +0200, Takashi Iwai wrote:
> 
> > Above all, the multiple indices don't work anyway with the snd_jack
> > stuff in the current form.  The index was introduced only for kjack,
> > and for HD-audio, snd_jack is provided just for a compatibility
> > reason, thus it doesn't matter much even if the multiple indices don't
> > work with it. 
> 
> > That being said, before going further, we need to consider how to
> > handle the input jack stuff with multiple indices.
> 
> What's the big problem with indexes and input (hopefully also extcon...)
> reporting?

No big problem, but we haven't defined it.
Should the index be embedded in the name string or handled in a
different way?

> > > -	snprintf(jack->name, sizeof(jack->name), "%s %s",
> > > +	snprintf(jack->name, sizeof(jack->name), "%s %s Jack",
> > >  		 card->shortname, jack->id);
> 
> > This breaks the compatibility with the existing code.
> > You must not change the name of the existing input jack element.
> > Some drivers create "Headphone" and some do "Headphone Jack", yes.
> > It's bad, but too late to change.
> 
> We can probably do something cheap like just check if there's a "Jack"
> already in the name?

Yes, I thought of it, too.  But there are some funky names like
"hook_switch".  Also, there is "Headphones", too.

So, IMO, the function should accept a special name for the input-jack
for compatibility reason while creating standard names for kjack, or
so...


Takashi