[alsa-devel] Grey noise with HDA Intel PCH

[Takashi Iwai]

At Thu, 14 Aug 2014 17:04:59 +0200,
Julian Wollrath wrote:
> 
> Am Thu, 14 Aug 2014 16:47:46 +0200
> schrieb Takashi Iwai <tiwai at suse.de>:
> 
> > At Thu, 14 Aug 2014 16:39:14 +0200,
> > Julian Wollrath wrote:
> > > 
> > > Am Thu, 14 Aug 2014 16:09:51 +0200
> > > schrieb Takashi Iwai <tiwai at suse.de>:
> > > 
> > > > At Thu, 14 Aug 2014 16:07:37 +0200,
> > > > Julian Wollrath wrote:
> > > > > 
> > > > > > > > > Simple mixer control 'Mic',0
> > > > > > > > >   Front Left: Playback 0 [0%] [-34.50dB] [on]
> > > > > > > > >   Front Right: Playback 0 [0%] [-34.50dB] [on]
> > > > > > > > 
> > > > > > > > This plays any noise from the mic input.
> > > > > > > Turning it off makes no difference since capture is turned
> > > > > > > off anyway:
> > > > > > 
> > > > > > This is a loopback mixer element, it has nothing to do with
> > > > > > capture stream.
> > > > > > 
> > > > > > The likely culprit of the static noises is the signal from the
> > > > > > analog loopback.  In some cases, you can disable the whole
> > > > > > loopback via "Loopback Mixing" mixer element on the fly.  In
> > > > > > some cases, you'd need to disable each mixer input (e.g. "Mic
> > > > > > Playback Switch"). In some cases (e.g. on some Sony and Dell
> > > > > > laptops), you'd need to disable the complete analog loopback
> > > > > > at the initialization.
> > > > > > 
> > > > > > The last one can be done via the early patching or sysfs
> > > > > > reconfiguration, pass "mixer_nid = 0" hint.  See HD-Audio.txt
> > > > > > for a brief instruction.
> > > > > Sadly, that did not help.
> > > > 
> > > > Give alsa-info.sh output after your change to verify whether you
> > > > did correctly.
> > > Here it is, cheers:
> > 
> > Thanks.  The setup looks OK, the path is:
> >   DAC (0x02) -> mixer (0x0c) -> mixer (0x14)
> > and the mixer mutes the loopback path (index 1).
> > 
> > Is it the state where you still hear the static noise?
> Yes, the alsa-info.sh script was executed, while hearing the static
> noise.

OK.  And if you mute "Speaker" or "Headphone", the noise is gone, too,
right?

> > Also, what if you use the module option for snd-hda-intel
> > model=nofixup or model=generic?
> That did not change anything either. Passing the "mixer_nid = 0" hint
> also did not get rid of the static noise, when loading snd-hda-intel
> with model=nofixup resp. model=generic.

Did you reboot with setting the option in /etc/modprobe.d/*?
Reloading the module might not work for such a problem.
In either way, there should be some difference in alsa-info.sh output,
e.g. more (or less) mixer items with the model option.


Takashi