[alsa-devel] [RFC] ASoC: snd_soc_jack for HDMI audio: does it make sense?
david.henningsson at canonical.com
Tue Aug 21 14:30:51 CEST 2012
On 08/21/2012 02:05 PM, 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.
This is wrong. PulseAudio uses the new ctljack API. I started out with
an implementation which used the input device API (sound/core/jack.c),
but since some people did not like this API, the ctljack API was
designed and implemented for PA to use, which it does (since PulseAudio
2.0 - the input device API implementation in PulseAudio was never merged
> - 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.
I don't know either why we have two different interfaces for jack
detection (not counting extcon) for driver writers. I think we should
merge jack and ctljack, as long as that does not mean you break anything
I'm relying on in ctljack.
Maybe something for discussion at Plumbers?
> Short term for drivers used on embedded systems I'd have to recommend
> extcon rather than anything ALSA-specific.
I thought that when Takashi did the new ctljack interface, that would
effectively deprecate the old input device interface, and that ctljack
was the new recommendation.
David Henningsson, Canonical Ltd.
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