ALSA: hda - Allow to enable/disable vmaster build explicitly

Another preliminary patch for the dual-codec support: since the
support of vmaster over multiple codecs is difficult, simply disable
it by a new flag to hda_codec struct.  A new user hint is added as
well for consistency.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Documentation/sound/hd-audio/notes.rst

@@ -494,6 +494,8 @@ add_hp_mic (bool)
 hp_mic_detect (bool)
     enable/disable the hp/mic shared input for a single built-in mic
     case; default true
+vmaster (bool)
+    enable/disable the virtual Master control; default true
 mixer_nid (int)
     specifies the widget NID of the analog-loopback mixer
 

sound/pci/hda/hda_generic.c

@@ -196,6 +196,9 @@ static void parse_user_hints(struct hda_codec *codec)
 	val = snd_hda_get_bool_hint(codec, "hp_mic_detect");
 	if (val >= 0)
 		spec->suppress_hp_mic_detect = !val;
+	val = snd_hda_get_bool_hint(codec, "vmaster");
+	if (val >= 0)
+		spec->suppress_vmaster = !val;
 
 	if (!snd_hda_get_int_hint(codec, "mixer_nid", &val))
 		spec->mixer_nid = val;
@@ -5033,7 +5036,7 @@ int snd_hda_gen_build_controls(struct hda_codec *codec)
 	}
 
 	/* if we have no master control, let's create it */
-	if (!spec->no_analog &&
+	if (!spec->no_analog && !spec->suppress_vmaster &&
 	    !snd_hda_find_mixer_ctl(codec, "Master Playback Volume")) {
 		err = snd_hda_add_vmaster(codec, "Master Playback Volume",
 					  spec->vmaster_tlv, slave_pfxs,
@@ -5041,7 +5044,7 @@ int snd_hda_gen_build_controls(struct hda_codec *codec)
 		if (err < 0)
 			return err;
 	}
-	if (!spec->no_analog &&
+	if (!spec->no_analog && !spec->suppress_vmaster &&
 	    !snd_hda_find_mixer_ctl(codec, "Master Playback Switch")) {
 		err = __snd_hda_add_vmaster(codec, "Master Playback Switch",
 					    NULL, slave_pfxs,

sound/pci/hda/hda_generic.h

@@ -229,6 +229,7 @@ struct hda_gen_spec {
 	unsigned int add_jack_modes:1; /* add i/o jack mode enum ctls */
 	unsigned int power_down_unused:1; /* power down unused widgets */
 	unsigned int dac_min_mute:1; /* minimal = mute for DACs */
+	unsigned int suppress_vmaster:1; /* don't create vmaster kctls */
 
 	/* other internal flags */
 	unsigned int no_analog:1; /* digital I/O only */