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

[Takashi Iwai]

At Tue, 21 Apr 2015 11:58:54 +0200,
Gabriele Mazzotta wrote:
> 
> 2015-04-19 19:26 GMT+02:00 Gabriele Mazzotta <gabriele.mzt at gmail.com>:
> > 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?
> 
> 
> Small update: I found that if I add a printk in alc_shutup_dell_xps13()
> or I increase the delay from 20ms to 200ms, I get the pop noise on
> start, with or without a551d91473 reverted. I will try to find out what
> this delay is exactly affecting.

Interesting.  I didn't think that increasing the delay affects (not
decreasing).

Maybe you'd be better to trace the verbs that are issued around the
headphone jack plugging.  The tracepoints are your friend.  See
HD-audio.txt for a brief instruction.


thanks,

Takashi