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Documentation / sound / alsa / HD-Audio-Controls.txt




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Based on kernel version 3.15.4. Page generated on 2014-07-07 09:04 EST.

1	This file explains the codec-specific mixer controls.
2	
3	Realtek codecs
4	--------------
5	
6	* Channel Mode
7	  This is an enum control to change the surround-channel setup,
8	  appears only when the surround channels are available.
9	  It gives the number of channels to be used, "2ch", "4ch", "6ch",
10	  and "8ch".  According to the configuration, this also controls the
11	  jack-retasking of multi-I/O jacks.
12	
13	* Auto-Mute Mode
14	  This is an enum control to change the auto-mute behavior of the
15	  headphone and line-out jacks.  If built-in speakers and headphone
16	  and/or line-out jacks are available on a machine, this controls
17	  appears.
18	  When there are only either headphones or line-out jacks, it gives
19	  "Disabled" and "Enabled" state.  When enabled, the speaker is muted
20	  automatically when a jack is plugged.
21	
22	  When both headphone and line-out jacks are present, it gives
23	  "Disabled", "Speaker Only" and "Line-Out+Speaker".  When
24	  speaker-only is chosen, plugging into a headphone or a line-out jack
25	  mutes the speakers, but not line-outs.  When line-out+speaker is
26	  selected, plugging to a headphone jack mutes both speakers and
27	  line-outs.
28	
29	
30	IDT/Sigmatel codecs
31	-------------------
32	
33	* Analog Loopback
34	  This control enables/disables the analog-loopback circuit.  This
35	  appears only when "loopback" is set to true in a codec hint
36	  (see HD-Audio.txt).  Note that on some codecs the analog-loopback
37	  and the normal PCM playback are exclusive, i.e. when this is on, you
38	  won't hear any PCM stream.
39	
40	* Swap Center/LFE
41	  Swaps the center and LFE channel order.  Normally, the left
42	  corresponds to the center and the right to the LFE.  When this is
43	  ON, the left to the LFE and the right to the center.
44	
45	* Headphone as Line Out
46	  When this control is ON, treat the headphone jacks as line-out
47	  jacks.  That is, the headphone won't auto-mute the other line-outs,
48	  and no HP-amp is set to the pins.
49	
50	* Mic Jack Mode, Line Jack Mode, etc
51	  These enum controls the direction and the bias of the input jack
52	  pins.  Depending on the jack type, it can set as "Mic In" and "Line 
53	  In", for determining the input bias, or it can be set to "Line Out"
54	  when the pin is a multi-I/O jack for surround channels.
55	
56	
57	VIA codecs
58	----------
59	
60	* Smart 5.1
61	  An enum control to re-task the multi-I/O jacks for surround outputs.
62	  When it's ON, the corresponding input jacks (usually a line-in and a
63	  mic-in) are switched as the surround and the CLFE output jacks.
64	
65	* Independent HP
66	  When this enum control is enabled, the headphone output is routed
67	  from an individual stream (the third PCM such as hw:0,2) instead of
68	  the primary stream.  In the case the headphone DAC is shared with a
69	  side or a CLFE-channel DAC, the DAC is switched to the headphone
70	  automatically.
71	
72	* Loopback Mixing
73	  An enum control to determine whether the analog-loopback route is
74	  enabled or not.  When it's enabled, the analog-loopback is mixed to
75	  the front-channel.  Also, the same route is used for the headphone
76	  and speaker outputs.  As a side-effect, when this mode is set, the
77	  individual volume controls will be no longer available for
78	  headphones and speakers because there is only one DAC connected to a
79	  mixer widget.
80	
81	* Dynamic Power-Control
82	  This control determines whether the dynamic power-control per jack
83	  detection is enabled or not.  When enabled, the widgets power state
84	  (D0/D3) are changed dynamically depending on the jack plugging
85	  state for saving power consumptions.  However, if your system
86	  doesn't provide a proper jack-detection, this won't work; in such a
87	  case, turn this control OFF.
88	
89	* Jack Detect
90	  This control is provided only for VT1708 codec which gives no proper
91	  unsolicited event per jack plug.  When this is on, the driver polls
92	  the jack detection so that the headphone auto-mute can work, while 
93	  turning this off would reduce the power consumption.
94	
95	
96	Conexant codecs
97	---------------
98	
99	* Auto-Mute Mode
100	  See Reatek codecs.
101	
102	
103	Analog codecs
104	--------------
105	
106	* Channel Mode
107	  This is an enum control to change the surround-channel setup,
108	  appears only when the surround channels are available.
109	  It gives the number of channels to be used, "2ch", "4ch" and "6ch".
110	  According to the configuration, this also controls the
111	  jack-retasking of multi-I/O jacks.
112	
113	* Independent HP
114	  When this enum control is enabled, the headphone output is routed
115	  from an individual stream (the third PCM such as hw:0,2) instead of
116	  the primary stream.
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