[alsa-devel] Grey noise with HDA Intel PCH

[Julian Wollrath]

Am Thu, 14 Aug 2014 17:26:58 +0200
schrieb Julian Wollrath <jwollrath at web.de>:

> Am Thu, 14 Aug 2014 17:11:32 +0200
> schrieb Takashi Iwai <tiwai at suse.de>:
> 
> > 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?
> No, if I mute "Speaker" (the internal laptop speaker) it is not gone.
> It is only gone, if I mute "Master" or have a headphone plugged in and
> mute "Headphone" or "Master".
> 
> More fascinating, it is not present, if the speaker is not muted and I
> disable powersaving via "echo '0' >
> '/sys/module/snd_hda_intel/parameters/power_save'" but even then, it
> is still present on the headphone.
And it is also present, if I mute only the speaker.

> > > > 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.
> No, I just unloaded every sound-related module and than loaded the
> module via "modprobe snd-hda-intel model=..." again.
> 
> > In either way, there should be some difference in alsa-info.sh
> > output, e.g. more (or less) mixer items with the model option.
> The difference is their, all the "Dock ..." entries were missing, when
> loading with the model="..." option.
> 
> Cheers,
> Julian