[alsa-devel] [RFC] ASoC: snd_soc_jack for HDMI audio: does it make sense?

Arun Raghavan arun.raghavan at collabora.co.uk
Fri Aug 24 09:10:37 CEST 2012

On Tue, 2012-08-21 at 13:05 +0100, Mark Brown wrote:
> On Tue, Aug 21, 2012 at 07:28:34AM +0200, Takashi Iwai wrote:
> > Ricardo Neri wrote:
> > > I was wondering about how much sense does it make to you guys use a 
> > > snd_soc_jack in this case?
> > HD-audio already uses the generic jack event for the HDMI/DP
> > connection change notification as well, so I think it would make sense
> > in general.
> The whole problem here is that we don't *have* a generic jack interface.
> We've got:
>  - sound/core/jack.c which was written to be a generic API and is used
>    by everything that does jack support currently.
>  - sound/core/ctljack.c which was added later and provides separate
>    in-kernel and userspace APIs and is currently only used by HDA.
>  - extcon which does have a good reason to be a separate API since that
>    it's not audio specific (and is likely to be picked up by Android as
>    the code was originally taken from there); it's currently not
>    supported by the frameworks in ALSA.  I'd suggest Pulse should be using
>    it too.
> This is a complete shambles for both driver authors and userspace, the
> ABI varies randomly with drivers and in theory driver authors have to
> implement everything three times which is just nuts.
> What I'd like to see happening is that we merge ctljack into jack (since
> only HDA is going to be affected by that change it seems like the right
> direction to make the merge) and also add extcon support, I have looked
> at the extcon support.
> Short term for drivers used on embedded systems I'd have to recommend
> extcon rather than anything ALSA-specific.

It's been in shambles for an absurdly long time. Would be good to
actually try to tackle it again at Plumbers or sth.

-- Arun

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