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

[Ian Munsie]

Hi Takashi,

> Check the value output by
>
>    hda-verb /dev/snd/hwC0D0 0x10 SET_PIN_SENSE 0
>    hda-verb /dev/snd/hwC0D0 0x10 GET_PIN_SENSE 0
>
> before and after plugging the headphone.
> Normally, the second line should show 0x80000000 after plugging the
> jack.

Doesn't look like it:

ian at button~ [i]> sudo hda-verb /dev/snd/hwC0D0 0x10 SET_PIN_SENSE 0
nid = 0x10, verb = 0x709, param = 0x0
value = 0x0
ian at button~ [i]> sudo hda-verb /dev/snd/hwC0D0 0x10 GET_PIN_SENSE 0
nid = 0x10, verb = 0xf09, param = 0x0
value = 0x0

<plug in headphones>

ian at button~ [i]> sudo hda-verb /dev/snd/hwC0D0 0x10 SET_PIN_SENSE 0
nid = 0x10, verb = 0x709, param = 0x0
value = 0x0
ian at button~ [i]> sudo hda-verb /dev/snd/hwC0D0 0x10 GET_PIN_SENSE 0
nid = 0x10, verb = 0xf09, param = 0x0
value = 0x0

> If it shows only zero for both plug/unplug, either the headphone pin
> assignment is wrong or the jack detection is broken.  In the former
> case, you can check by adjusting the headphone volume or mute mixer
> control and see whether it really happens on the machine.

I can confirm that adjusting the headphone volume & mute with
alsamixer does correctly adjust the headphone volume, so I guess the
jack detection isn't working.

It seems that pulseaudio was doing some funny things with the mute
controls (muting any one of headphones, speakers & master would mute
all three & all would have to be individually unmuted before getting
sound again - I guess pulseaudio doesn't expect anyone to adjust the
sound card mixer directly while it is running), so I temporarily
uninstalled it again for this test.


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%).

Cheers,
-Ian

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