ALSA: hda - Disable Headphone Mic boost for ALC662

When headphone mic boost is above zero, some 10 - 20 second delay
might occur before the headphone mic is operational.
Therefore disable the headphone mic boost control (recording gain is
sufficient even without it).

(Note: this patch is not about the headset mic, it's about the less
common mic-in only mode.)

BugLink: https://bugs.launchpad.net/bugs/1454235Suggested-by: Kailang Yang <kailang@realtek.com>
Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/patch_realtek.c

@@ -4228,6 +4228,11 @@ static void alc_fixup_headset_mode_alc662(struct hda_codec *codec,
 	if (action == HDA_FIXUP_ACT_PRE_PROBE) {
 		spec->parse_flags |= HDA_PINCFG_HEADSET_MIC;
 		spec->gen.hp_mic = 1; /* Mic-in is same pin as headphone */
+
+		/* Disable boost for mic-in permanently. (This code is only called
+		   from quirks that guarantee that the headphone is at NID 0x1b.) */
+		snd_hda_codec_write(codec, 0x1b, 0, AC_VERB_SET_AMP_GAIN_MUTE, 0x7000);
+		snd_hda_override_wcaps(codec, 0x1b, get_wcaps(codec, 0x1b) & ~AC_WCAP_IN_AMP);
 	} else
 		alc_fixup_headset_mode(codec, fix, action);
 }