[alsa-devel] Mic detection on Mackbook Pro 12,1 (CS4208)

[Paulo Fidalgo]

Hi,

After reporting the issue on bugzilla
(https://bugzilla.kernel.org/show_bug.cgi?id=155601) I felt I could do
more in order to try to get a patch to fix the issue.

Basically when I plug an headset(mic+headphone), it only detects the
headphone not the mic.

Since I assumed the "memory address" of the 0x18 pin is wrong, I've
tried to change some values in order to get it working.
I have tries both ways:

1. By changing the kernel souce(sound/pci/hda/patch_cirrus):
in the function
static void cs4208_fixup_mac(struct hda_codec *codec,
                 const struct hda_fixup *fix, int action)

I've added an configuration to set the address of the 0x18.

Then create a script to remove the module, compile, load and test via
arecord if it's working.

2. use the user_pin_configs
basically I've iterated for the range of memory addresses found in the
card config and try to apply them:

for (( num=0x002b4020; num <= 0x90a60100; num+=1 ))
 do
pulseaudio -k
ADDRESS=$(printf "0x%08x\n" $num)
echo "0x18 $ADDRESS" | sudo tee /sys/class/sound/hwC1D0/user_pin_configs
echo "0x1c 0x400000f0" | sudo tee /sys/class/sound/hwC1D0/user_pin_configs
echo 1 | sudo tee /sys/class/sound/hwC1D0/reconfig
pulseaudio -D
arecord -d 5 -vvv -f dat /dev/null 2>&1 | grep -Po " 1\d+%"
done

but since I need to use the computer, I'm doing this in batches.

Both address we're found by alsa-config as the pin addresses.

Now my question is, is there a better way (without brute force) to get
the right address?
Could be anything else, other than the address?

I also have MacOS installed, but from what I've found there's no way
to know the address in MacOS, if there's a way, please point me ;)

Best regards,

Paulo Fidalgo