1 ==================
2 ALSA Jack Controls
3 ==================
4
5 Why we need Jack kcontrols
6 ==========================
7
8 ALSA uses kcontrols to export audio controls(s
9 to user space. This means userspace applicatio
10 switch off headphones and switch on speakers w
11 plugged in.
12
13 The old ALSA jack code only created input devi
14 jack. These jack input devices are not readabl
15 that run as non root.
16
17 The new jack code creates embedded jack kcontr
18 can be read by any process.
19
20 This can be combined with UCM to allow userspa
21 intelligently based on jack insertion or remov
22
23 Jack Kcontrol Internals
24 =======================
25
26 Each jack will have a kcontrol list, so that w
27 and attach it to the jack, at jack creation st
28 kcontrol to an existing jack, at anytime when
29
30 Those kcontrols will be freed automatically wh
31
32 How to use jack kcontrols
33 =========================
34
35 In order to keep compatibility, snd_jack_new()
36 adding two params:
37
38 initial_kctl
39 if true, create a kcontrol and add it to the
40 phantom_jack
41 Don't create a input device for phantom jack
42
43 HDA jacks can set phantom_jack to true in orde
44 jack and set initial_kctl to true to create an
45 the correct id.
46
47 ASoC jacks should set initial_kctl as false. T
48 assigned as the jack kcontrol name.
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