[alsa-devel] Separate input and output jacks for one UCM device?

[Dylan Reid]

On Wed, Apr 15, 2015 at 8:39 AM, Tanu Kaskinen
<tanu.kaskinen at linux.intel.com> wrote:
> On Tue, 2015-04-07 at 23:37 +0300, Tanu Kaskinen wrote:
>> On Thu, 2015-04-02 at 08:28 -0700, Dylan Reid wrote:
>> > On Wed, Apr 1, 2015 at 5:27 AM, Liam Girdwood
>> > <liam.r.girdwood at linux.intel.com> wrote:
>> > > On Tue, 2015-03-31 at 19:49 +0300, Tanu Kaskinen wrote:
>> > >> So is your preference that UCM configuration authors are forced to
>> > >> define simplex devices to deal with headset jacks, rather than using
>> > >> duplex devices and defining "PlaybackJackControl" and
>> > >> "CaptureJackControl" separately? (I don't personally mind either way.)
>> > >
>> > > I don't really mind either, but what's easier for audio servers like
>> > > pulseaudio that will be the main UCM clients ? I guess that pulseaudio,
>> > > CRAS, and other audio servers probably deal with simplex PCM streams
>> > > internally so mapping to simplex jacks/devices might be better ?
>> >
>> > There is an advantage to having a separate device for the headphone and mic
>> > even if they are connected to the same jack.  The user can enable one and not
>> > the other, most commonly to use the headphones but record from the built-in mic,
>> > ignoring the headset mic.  Because of this we require all ChromeOS devices to
>> > support separate reporting and selection of headphone/mic on the headset jack.
>> > There is always one UCM device and one user-visible i/o node per jack.
>>
>> I'm not sure what you mean... "There is always one UCM device [...] per
>> jack" sounds like you want there to be only one device representing
>> headset, but on the other hand you talk about it being advantageous to
>> have a separate device for the headphone and mic... Can you clarify the
>> number of UCM devices per physical headset jack?
>
> Ping? I'd like to get this clarified, because depending on what CRAS
> does, we may or may not have to change the use-case.h documentation (and
> PulseAudio code).

Sorry I missed this.  CRAS handles separate UCM devices for the
headphone and mic of a combo jack.  However there is no support for
handling a "Headset Jack" kcontrol or input event.  We have ensured
all our platforms are capable of detecting if a mic is present and
that they report the headphone and mic as separate jacks.

>
> --
> Tanu
>