[alsa-devel] RFC: Jack-detection control elements on HD-audio

Takashi Iwai tiwai at suse.de
Fri Jun 19 14:31:18 CEST 2009

At Fri, 19 Jun 2009 14:21:26 +0200,
Lennart Poettering wrote:
> On Fri, 19.06.09 10:04, Takashi Iwai (tiwai at suse.de) wrote:
> > Hi,
> > 
> > yet another thing I've worked recently on is a bit more generalized
> > framework for jack-sense reporting for HD-audio.  This supersedes the
> > existing jack-sense reporting via the input layer.  In addition, it
> > gives the corresponding control elements.
> > 
> > For example, you'll have "Jack HP-Out" (or a bit more verbose like
> > "Jack HP-Out at Ext Rear") control via control API as well as other
> > mixer controls.  This can notify when a jack is plugged/unplugged.
> > But, another big win is that you can read the current pin sense just
> > by reading this element.
> > 
> > I think this is a sort of feature Lennart wanted for PA.
> > Lennart, does it make sense?
> Yes. I think it would. Also, if we can use the name of a control to
> find the jack sensing control for it this would be great. I.e. if we
> have a control "Headphone" and the Jack sensing control for it would
> then be called "Headphone Jack" or so, this would be great! 

Ah, that's a good point.  So far, there is no strict connection
between them since the jacks are physical while the volume controls
are logical.  But, they could correlate a bit more with each other.
Another TODO.

As posted in another mail, some extra information such as jack
location can be stored in the control TLV.  So they can be really
named as "Headphone Jack".



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