At Thu, 12 Mar 2015 20:13:05 +0100, Vasil Zlatanov wrote:

Applied both patches against 3.18.6-1 and correctly resolved all issues.

Good to hear, I queued both patches now. They'll be backported to stable kernels once when merged to upstream.

thanks,

Takashi

On Thu, Mar 12, 2015 at 11:38:39AM +0100, Takashi Iwai wrote:

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At Wed, 11 Mar 2015 23:26:00 +0100, Vasil Zlatanov wrote:

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Issue as seen on reddit thread: https://www.reddit.com/r/linux/comments/1kccbk/alsa_bug_driving_me_crazy_ple...

A common problem for Apple Macbook Air 5.2 users where microphone does not work after system resume. As users have noted microphone starts working ones again when the volume is changed in alsa-mixer.

alsa-info dumps are attached showing before and after being adjusted (where before causes microphone not to work while in after it does)

IRC user 'debianuser' kindly helped out and found that using the two following commands fix the issue:

amixer -cPCH set "Capture" 0% nocap amixer -cPCH set "Capture" 100% cap

In my experience both are required and they seem to have the same effect as manually changing the volume level in alsamixer, and as such resolve the issue (until another suspend when they have to be run again).

This might be due to the single ADC amp. The ADC widgets have multiple inputs and usually they have individual amp volumes. But some codecs give only a single volume for all inputs.

There is a flag in the driver to change the control for that. The patch below enables it.

diff --git a/sound/pci/hda/patch_cirrus.c b/sound/pci/hda/patch_cirrus.c index 1589c9bcce3e..dd2b3d92071f 100644 --- a/sound/pci/hda/patch_cirrus.c +++ b/sound/pci/hda/patch_cirrus.c @@ -584,6 +584,7 @@ static int patch_cs420x(struct hda_codec *codec) return -ENOMEM;

spec->gen.automute_hook = cs_automute;

• codec->single_adc_amp = 1;

  snd_hda_pick_fixup(codec, cs420x_models, cs420x_fixup_tbl, cs420x_fixups);

Alternatively, you can pass "single_adc_smp = true" hint in the firmware patch passed via patch option. See Documentation/sound/alsa/HD-Audio.txt for details.

...

As of now I'm resolving this issue by creating a service that is to run after resume from susspend with the given amixer commands to renable the microphone.

The second issue, which is also in the reddit thread, is that the microphine is mono and when recording only right channel audio is seen. For me this broke programs such as mumble and skype.

A alsa-info output with coefficients is attached.

'debianuser' managed to find a solution to this issue well, resolving it by running the following two commands:

hda-verb /dev/snd/hwC0D0 0x11 SET_COEF_INDEX 2 hda-verb /dev/snd/hwC0D0 0x11 SET_PROC_COEF 0x102a

After one runs them a single time after boot, the channels collectly show and programs issues are resolved. 'debianuser' mentions that the sources for the commands are available in the kernel and applied to the macbook 8.1 model, but not to mine.

Yes, it's the very same workaround for MBP8,1. You can pass model=mbp81 option. If it works, you can just add a sline to cs420x_fixup_tbl[] something like

@@ -393,6 +393,7 @@ static const struct snd_pci_quirk cs420x_fixup_tbl[] = { SND_PCI_QUIRK(0x106b, 0x1c00, "MacBookPro 8,1", CS420X_MBP81), SND_PCI_QUIRK(0x106b, 0x2000, "iMac 12,2", CS420X_IMAC27_122), SND_PCI_QUIRK(0x106b, 0x2800, "MacBookPro 10,1", CS420X_MBP101),

• SND_PCI_QUIRK(0x106b, 0x5600, "MacBookAir 5,2", CS420X_MBP81), SND_PCI_QUIRK(0x106b, 0x5b00, "MacBookAir 4,2", CS420X_MBA42), SND_PCI_QUIRK_VENDOR(0x106b, "Apple", CS420X_APPLE), {} /* terminator */

Takashi

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