[alsa-devel] Grey noise with HDA Intel PCH

[Takashi Iwai]

At Thu, 14 Aug 2014 18:29:19 +0200,
Julian Wollrath wrote:
> 
> > > > > > 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".
> > 
> > Interesting.  The "Speaker" mute changes "Speaker Playback Switch",
> > and as you can see in alsa-info.sh output, this toggles the mute of
> > the speaker pin NID 0x14, i.e. the endpoint.  If "Master" influences,
> > it means to mute *both* Headphone and Speaker mutes would work.
> > Could you check this?
> Muting both Headphone and Speaker does not work for the static noise on
> the speaker.

Then check what's the difference in codec proc content between the two
cases: Master=mute and Headphone+Speaker=mute.

> > > 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.
> > 
> > Hm.  Is the noise audible when you playback a PCM stream, too?
> > For example, you can play a silent stream.
> Yes, then it is audible.
> 
> > > > > > 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.
> > 
> > Then always test with reboot.  The problem is about the
> > vendor-specific setups, and it's often sticky unless the cold boot.
> > At best, do the cold boot.  The warm boot doesn't cure always.
> Ok, I tested with a reboot but that did not help.
> 
> > > > 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.
> > 
> > Yes, and you should also see the difference in the kernel messages.
> > 
> > Another thing to check is to swap the DAC assignment.  There was a
> > similar problem on some Sony laptops, and we had to swap the DAC
> > assignment since the hardware seems to have some implicit assumption
> > of the DAC.  A test patch is below.
> Thanks, but sadly the patch did not help.

I have no much other clue, so far.  The rest you can test is to toggle
EAPD, toggle GPIO pin, and change the different pin setups, e.g. put
VREF or HP amp bit on any (even unused) pins.


Takashi