[PATCH] ALSA: hda/realtek: add mic quirk for Acer SF314-42

[Alexander Monakov]

On Wed, 28 Jul 2021, Takashi Iwai wrote:

> > 1) at high enough gain, recording the microphone is picking up what is
> > being played via the headphones; maybe it's supposed to be like that,
> > but it surprised me;
> 
> Hrm, that doesn't sound right.  Some internal loopback in the codec?
> Dunno.  It doesn't pick up the sound physically, right?

How can I tell? If I don't have anything plugged into the jack, playback
uses the built-in speakers. In that case there's no feedback. And if I
plug in a headset or common headphones, then built-in speakers are automatically
muted, and recording the mic can pick up the output signal.

Is there a way to forcefully direct output to the jack instead of built-in
speakers even when there isn't anything plugged in?

I am sure it is not picking the sound over the air, but I'm considering it's
picking it up electrically near the jack somehow.

> > 2) there is a very noticeable "pop" when plugging the headset in/out,
> > accompanied by
> > 
> > pcieport 0000:00:08.1: PME: Spurious native interrupt!
> > pcieport 0000:00:08.1: PME: Spurious native interrupt!
> > 
> > in dmesg. I'd appreciate info and any help about this issue.
> 
> The pop noise is often a thing with the codec and there are a bunch of
> different workarounds found in the driver.  But the spurious interrupt
> is more worrisome.  Is the PCI slot corresponding to the HD-audio
> controller?

No, it's actually the PCI bridge under which the HDA core resides:

00:08.1 PCI bridge: Advanced Micro Devices, Inc. [AMD] Renoir Internal PCIe GPP Bridge to Bus
00:08.1/03:00.6 Audio device: Advanced Micro Devices, Inc. [AMD] Family 17h (Models 10h-1fh) HD Audio Controller

Note that I have autosuspend enabled for PCI devices. If I disable PCI
autosuspend for the 03:00.6 HDA device, there's no "pop" and no spurious
interrupt. My understanding that the chip generates a power management event
when it senses a jack plug/unplug event while suspended. Apparently something
about the PME interrupt is not fully in order?

> As of now, I'm inclined to take your patch as is, at least as a
> first-aid workaround.  Let's see whether we get a better development
> soonish.

*nod*, I will appreciate it!

Thank you.
Alexander