[alsa-devel] No sound from internal speaker on 2013 Macbook Air 6, 1

[Raymond Yau]

>
>
> One other weird thing I noticed while testing this is that setting the
> volume to 0% and/or muting does the controls does not seem to
> completely mute the sound - it is just really quiet (quiet enough not
> to be an issue for me). Some observations:
>
> __Speakers__
> Master: Mute AND/OR Speakers: Mute
> --> Speakers are muted.
>
> Master: 0% AND Speakers: 0%
> --> Sound still comes from speakers, but is very quiet.
>
> Master: 0%
> --> speaker control affects volume.
>
> __Headphones__
> Master: 0% AND/OR Headphones: 0%
> --> Sound still comes from headphones at low volume
> (if either control is 0%, the volume of the other control has no
> effect - both have to be non-zero to raise the volume).
>
> Master: Mute AND/OR Headphones: Mute
> --> Sound still comes from headphones, though is fairly quiet (much
> lower than 0%).
>

Because the driver select the amp at the pin complex of the headphone
instead of the amp at the audio output

These amps have different dB min

Node 0x02 [Audio Output] wcaps 0xd043d: Stereo Amp-Out Stripe
  Device: name="ID 4208 Analog", type="Audio", device=0
  Amp-Out caps: ofs=0x7f, nsteps=0x7f, stepsize=0x01, mute=1
  Amp-Out vals:  [0x7f 0x7f]
  Converter: stream=8, channel=0
  PCM:
    rates [0x7f0]: 32000 44100 48000 88200 96000 176400 192000
    bits [0x1e]: 16 20 24 32
    formats [0x3]: PCM FLOAT
  Power states:  D0 D3 EPSS
  Power: setting=D0, actual=D0
  Delay: 13 samples
Node 0x03 [Audio Output] wcaps 0xd043d: Stereo Amp-Out Stripe
  Control: name="Speaker Playback Volume", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Control: name="Speaker Playback Switch", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Amp-Out caps: ofs=0x7f, nsteps=0x7f, stepsize=0x01, mute=1
  Amp-Out vals:  [0x7f 0x7f]
  Converter: stream=8, channel=0
  PCM:
    rates [0x7f0]: 32000 44100 48000 88200 96000 176400 192000
    bits [0x1e]: 16 20 24 32
    formats [0x3]: PCM FLOAT
  Power states:  D0 D3 EPSS
  Power: setting=D0, actual=D0
  Delay: 13 samples

Node 0x10 [Pin Complex] wcaps 0x40058d: Stereo Amp-Out
  Control: name="Headphone Playback Volume", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Control: name="Headphone Playback Switch", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Control: name="Headphone Jack", index=0, device=0
  Amp-Out caps: ofs=0x42, nsteps=0x42, stepsize=0x03, mute=1
  Amp-Out vals:  [0x42 0x42]
  Pincap 0x0000001c: OUT HP Detect
  Pin Default 0x032b401f: [Jack] HP Out at Ext Left
    Conn = Comb, Color = Green
    DefAssociation = 0x1, Sequence = 0xf
  Pin-ctls: 0xc0: OUT HP
  Unsolicited: tag=01, enabled=1
  Power states:  D0 D3 EPSS
  Power: setting=D0, actual=D0
  Connection: 1
     0x02