2015-04-24 8:13 GMT+02:00 Takashi Iwai tiwai@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