[alsa-devel] [PATCH 1/4] ALSA: Added jack detection kcontrol support

[Felipe Tonello]

Mark,

On Fri, Jul 26, 2013 at 11:54 AM, Mark Brown <broonie at kernel.org> wrote:
> On Fri, Jul 26, 2013 at 11:25:30AM -0700, Felipe F. Tonello wrote:
>
>> +
>> +     /* Update ALSA KControl interface */
>> +     snd_kctl_jack_report((struct snd_card *)jack->kctl->private_data, jack->kctl, !!status);
>
> This isn't ideal for multi-function jacks like headsets - it will report
> a single boolean value for the jack regardless of what's plugged in
> meaning userpace can't do things like figure out if a headset or
> headphone is present.  It's probably OK for any realistic input button
> since you're not going to get an input button without other things being
> present.

The KControl for Jack is boolean anyway. You can check it with "amixer
contents". user-space can figure out based on the control name. At
least PulseAudio does that way.

>
> What I'd expect to happen here is that for multi function jacks we
> create a control per function if the controls are valid.

Do you mean based on snd_jack_types?

Felipe Tonello