linux-kernel - Re: [PATCH 1/4] ALSA: Added jack detection kcontrol support

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Message-ID: <20130727122524.GH9858@sirena.org.uk>
Date:	Sat, 27 Jul 2013 13:25:24 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Felipe Tonello <eu@...ipetonello.com>
Cc:	alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
	Takashi Iwai <tiwai@...e.de>,
	David Henningsson <david.henningsson@...onical.com>,
	Wang Xingchao <xingchao.wang@...ux.intel.com>,
	Jaroslav Kysela <perex@...ex.cz>
Subject: Re: [PATCH 1/4] ALSA: Added jack detection kcontrol support

On Fri, Jul 26, 2013 at 04:13:40PM -0700, Felipe Tonello wrote:
> On Fri, Jul 26, 2013 at 3:48 PM, Mark Brown <broonie@...nel.org> wrote:

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

> Ok, so the idea is just to change the control to type integer instead
> of boolean, right?
> Because as you say, the user will be able to check the type of jack
> based on the status value, right?

It might be more idiomatic and more compatible with userspace to create
multiple controls for the jack, there was some discussion of this in the
past I think but I can't remember the result.

> > Yes.  If there's only one function supported the current code is fine
> > but for multiple functions it's going to discard useful information.

> So, what do you suggest to do that? I'm not sure if I understand what
> you are saying.
> When you mean function, do you mean the SND_JACK_BTN_n or the the jack
> types, such as SND_JACK_HEADPHONE, and so on?

The jack types, the buttons definitely sohuld be going up as input
events.

> If a codec creates a jack type SND_JACK_HEADSET (= SND_JACK_HEADPHONE
> | SND_JACK_MICROPHONE). It should be created two controls, name +
> "Headphone Jack" and name + "Microphone Jack"? If so, what about the
> status to report? How to know which control to report?

The drivers report a bitmask for status.

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