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

[Gabriele Mazzotta]

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.

Gabriele