[alsa-devel] Pop noise on startup when headphones are plugged in (Dell XPS13 9333)

[Takashi Iwai]

At Fri, 24 Apr 2015 17:14:24 +0200,
Gabriele Mazzotta wrote:
> 
> 2015-04-24 8:13 GMT+02:00 Takashi Iwai <tiwai at suse.de>:
> > At Thu, 23 Apr 2015 21:12:50 +0200,
> > Gabriele Mazzotta wrote:
> >>
> >> On Sunday 19 April 2015 19:26:58 Gabriele Mazzotta wrote:
> >> > Hi,
> >> >
> >> > I've recently found that commit a551d91473 ("ALSA: hda - Use regmap for
> >> > command verb caches, too") is somehow causing a pop noise on startup
> >> > when headphones are plugged in, but I couldn't figure out the exact
> >> > cause. Was this observed on other systems (mine is a Dell XPS13 9333,
> >> > Realtek ALC3661)? Does anyone have any idea of what the cause might be?
> >>
> >> Hi,
> >>
> >> I don't know why a551d91473 caused the issue, but I found the real
> >> cause of problem.
> >>
> >> On init, create_input_ctls() sets the vref of nid 0x19 to 80 (as
> >> returned by snd_hda_get_default_vref()), but it should be set to HIZ.
> >> This is not so different from the issue addressed by f38663ab5c
> >> ("ALSA: hda - Set internal mic as default input source on Dell XPS 13 9333").
> >>
> >> I made a patch to prevent this from happening.
> >>
> >> Setting the vref is not necessary since alc_update_headset_mode() will
> >> take care of it.
> >>
> >> Should I maybe add a new flag instead of using suppress_hp_mic_detect?
> >
> > Yeah, that's better.  Although the flag is currently unused, it's
> > provided for a different purpose (to skip the headphone mic detection;
> > which is different from "headset" mic).
> >
> > I wonder, though, whether the patch below improves anything.
> > A similar patch was in the development series in the past, but I had
> > to drop it because it caused behavior error.  But now I tried again,
> > and it seems working.
> >
> >
> > Takashi
> 
> The patch did no harm, but didn't solve the problem.

OK, so the problem doesn't seem relevant with the runtime PM, which
was the usual suspect.

My patch should reduce the actual verb writes, so it would be nice to
have even if it doesn't fix your problem.  But maybe I'll postpone it
as a 4.2 material.


thanks,

Takashi