[alsa-devel] Signaling user-space through kcontrol

Mark Brown broonie at opensource.wolfsonmicro.com
Wed Sep 28 12:48:55 CEST 2011

On Wed, Sep 28, 2011 at 12:26:43AM -0700, Patrick Lai wrote:
> On 9/28/2011 12:03 AM, Vinod Koul wrote:

> >> Main one is detection of short circuiting headphone For this case,
> >> there is no need for extra payload. In case of there is need to pass
> >> back some payload, I presume user-space application can simply call the
> >> get function upon receiving notification.

> > And what would userspace do with that information? Apart from logging
> > this, is there anything useful we can do with such info

> Well, it's up to user-space application to decide. I suppose
> application would not allow audio route to headphone/headset at this
> point.

Something like that specific example should probably be reported via the
snd_jack accessory detection infrastructure which can then offer a
consistent interface between all sound cards with minimal work on the
part of the individual driver.  There will doubtless be other examples

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