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kernel/linux-imx6_3.14.28/Documentation/sound/alsa/HD-Audio-Controls.txt 4.35 KB
6b13f685e   김민수   BSP 최초 추가
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  This file explains the codec-specific mixer controls.
  
  Realtek codecs
  --------------
  
  * Channel Mode
    This is an enum control to change the surround-channel setup,
    appears only when the surround channels are available.
    It gives the number of channels to be used, "2ch", "4ch", "6ch",
    and "8ch".  According to the configuration, this also controls the
    jack-retasking of multi-I/O jacks.
  
  * Auto-Mute Mode
    This is an enum control to change the auto-mute behavior of the
    headphone and line-out jacks.  If built-in speakers and headphone
    and/or line-out jacks are available on a machine, this controls
    appears.
    When there are only either headphones or line-out jacks, it gives
    "Disabled" and "Enabled" state.  When enabled, the speaker is muted
    automatically when a jack is plugged.
  
    When both headphone and line-out jacks are present, it gives
    "Disabled", "Speaker Only" and "Line-Out+Speaker".  When
    speaker-only is chosen, plugging into a headphone or a line-out jack
    mutes the speakers, but not line-outs.  When line-out+speaker is
    selected, plugging to a headphone jack mutes both speakers and
    line-outs.
  
  
  IDT/Sigmatel codecs
  -------------------
  
  * Analog Loopback
    This control enables/disables the analog-loopback circuit.  This
    appears only when "loopback" is set to true in a codec hint
    (see HD-Audio.txt).  Note that on some codecs the analog-loopback
    and the normal PCM playback are exclusive, i.e. when this is on, you
    won't hear any PCM stream.
  
  * Swap Center/LFE
    Swaps the center and LFE channel order.  Normally, the left
    corresponds to the center and the right to the LFE.  When this is
    ON, the left to the LFE and the right to the center.
  
  * Headphone as Line Out
    When this control is ON, treat the headphone jacks as line-out
    jacks.  That is, the headphone won't auto-mute the other line-outs,
    and no HP-amp is set to the pins.
  
  * Mic Jack Mode, Line Jack Mode, etc
    These enum controls the direction and the bias of the input jack
    pins.  Depending on the jack type, it can set as "Mic In" and "Line 
    In", for determining the input bias, or it can be set to "Line Out"
    when the pin is a multi-I/O jack for surround channels.
  
  
  VIA codecs
  ----------
  
  * Smart 5.1
    An enum control to re-task the multi-I/O jacks for surround outputs.
    When it's ON, the corresponding input jacks (usually a line-in and a
    mic-in) are switched as the surround and the CLFE output jacks.
  
  * Independent HP
    When this enum control is enabled, the headphone output is routed
    from an individual stream (the third PCM such as hw:0,2) instead of
    the primary stream.  In the case the headphone DAC is shared with a
    side or a CLFE-channel DAC, the DAC is switched to the headphone
    automatically.
  
  * Loopback Mixing
    An enum control to determine whether the analog-loopback route is
    enabled or not.  When it's enabled, the analog-loopback is mixed to
    the front-channel.  Also, the same route is used for the headphone
    and speaker outputs.  As a side-effect, when this mode is set, the
    individual volume controls will be no longer available for
    headphones and speakers because there is only one DAC connected to a
    mixer widget.
  
  * Dynamic Power-Control
    This control determines whether the dynamic power-control per jack
    detection is enabled or not.  When enabled, the widgets power state
    (D0/D3) are changed dynamically depending on the jack plugging
    state for saving power consumptions.  However, if your system
    doesn't provide a proper jack-detection, this won't work; in such a
    case, turn this control OFF.
  
  * Jack Detect
    This control is provided only for VT1708 codec which gives no proper
    unsolicited event per jack plug.  When this is on, the driver polls
    the jack detection so that the headphone auto-mute can work, while 
    turning this off would reduce the power consumption.
  
  
  Conexant codecs
  ---------------
  
  * Auto-Mute Mode
    See Reatek codecs.
  
  
  Analog codecs
  --------------
  
  * Channel Mode
    This is an enum control to change the surround-channel setup,
    appears only when the surround channels are available.
    It gives the number of channels to be used, "2ch", "4ch" and "6ch".
    According to the configuration, this also controls the
    jack-retasking of multi-I/O jacks.
  
  * Independent HP
    When this enum control is enabled, the headphone output is routed
    from an individual stream (the third PCM such as hw:0,2) instead of
    the primary stream.