[alsa-devel] Audio crackles with 4.1-rc1

[Mihai Donțu]

On Thu, 11 Jun 2015 07:01:13 +0200 Takashi Iwai wrote:
> At Thu, 11 Jun 2015 01:12:36 +0300, Mihai Donțu wrote:
> > On Wed, 10 Jun 2015 20:23:01 +0200 Takashi Iwai wrote:
> > > From: Takashi Iwai <tiwai at suse.de>
> > > Subject: [PATCH] ALSA: hda - Reduce click noise at power up
> > > 
> > > Some machines suffer from click noises at power up with the recent
> > > kernels, and this seems triggered at the power transition and the
> > > immediate verb executions.  As a workaround, put a short delay (10ms)
> > > right after the D0 transition.
> > > 
> > > There are a few places that have the same kind of delays, especially
> > > in the resume path.  I guess they can be removed (or reduced) after
> > > this patch.  But, since the delay is relatively small, let's do it
> > > later as a cleanup.
> > > 
> > > Reported-by: Mihai Donțu <mihai.dontu at gmail.com>
> > > Signed-off-by: Takashi Iwai <tiwai at suse.de>
> > > ---
> > >  sound/pci/hda/hda_codec.c | 3 +++
> > >  1 file changed, 3 insertions(+)
> > > 
> > > diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
> > > index b7782212dd64..38f5509ee52f 100644
> > > --- a/sound/pci/hda/hda_codec.c
> > > +++ b/sound/pci/hda/hda_codec.c
> > > @@ -3077,6 +3077,9 @@ static unsigned int hda_set_power_state(struct hda_codec *codec,
> > >  			break;
> > >  	}
> > >  
> > > +	if (power_state == AC_PWRST_D0)
> > > +		msleep(10);
> > > +
> > >  	return state;
> > >  }
> > >  
> > 
> > I take back my previous observations. I was at work and did not have
> > access to headphones (one of those days). Now I'm at home, it's 1 AM,
> > very quiet, and I notice the following:
> > 
> >  * on speakers: the click reproduces but with _very_ low amplitude;
> >    msleep(100) is unnoticeable, but msleep(10) is, barely;
> >  * on headphones: the moment I plug them I hear a loud static sound
> >    (like an old, untuned AM radio). If I play something, the static
> >    disappears. If I pause, the static returns after ~15s.
> 
> OK, then the patch is no-go.  We need a bit deeper analysis.
> 
> About the headphone problem: don't you get the same issue with 4.0.x?
> Please take alsa-info.sh outputs on both 4.0.x and 4.1 before and
> after plugging the headphone, and attach the outputs.
> (Run the script with --no-upload option.)

No, 4.0.5 and all previous kernels (>= 3.12) are OK. I have attached a
small tarball with the two files produced by alsa-info.sh.

Thanks,

-- 
Mihai Donțu
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