ALSA: dummy: allow disabling mixer controls

To make the testing of deactivated mixer controls easier (and for people
with common hardware, possible), add a control that deactivates some
other controls.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>

sound/drivers/dummy.c

@@ -134,6 +134,9 @@ struct snd_dummy {
 	spinlock_t mixer_lock;
 	int mixer_volume[MIXER_ADDR_LAST+1][2];
 	int capture_source[MIXER_ADDR_LAST+1][2];
+	int iobox;
+	struct snd_kcontrol *cd_volume_ctl;
+	struct snd_kcontrol *cd_switch_ctl;
 	const struct dummy_timer_ops *timer_ops;
 };
 
@@ -817,6 +820,57 @@ static int snd_dummy_capsrc_put(struct snd_kcontrol *kcontrol, struct snd_ctl_el
 	return change;
 }
 
+static int snd_dummy_iobox_info(struct snd_kcontrol *kcontrol,
+				struct snd_ctl_elem_info *info)
+{
+	const char *const names[] = { "None", "CD Player" };
+
+	return snd_ctl_enum_info(info, 1, 2, names);
+}
+
+static int snd_dummy_iobox_get(struct snd_kcontrol *kcontrol,
+			       struct snd_ctl_elem_value *value)
+{
+	struct snd_dummy *dummy = snd_kcontrol_chip(kcontrol);
+
+	value->value.enumerated.item[0] = dummy->iobox;
+	return 0;
+}
+
+static int snd_dummy_iobox_put(struct snd_kcontrol *kcontrol,
+			       struct snd_ctl_elem_value *value)
+{
+	struct snd_dummy *dummy = snd_kcontrol_chip(kcontrol);
+	int changed;
+
+	if (value->value.enumerated.item[0] > 1)
+		return -EINVAL;
+
+	changed = value->value.enumerated.item[0] != dummy->iobox;
+	if (changed) {
+		dummy->iobox = value->value.enumerated.item[0];
+
+		if (dummy->iobox) {
+			dummy->cd_volume_ctl->vd[0].access &=
+				~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
+			dummy->cd_switch_ctl->vd[0].access &=
+				~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
+		} else {
+			dummy->cd_volume_ctl->vd[0].access |=
+				SNDRV_CTL_ELEM_ACCESS_INACTIVE;
+			dummy->cd_switch_ctl->vd[0].access |=
+				SNDRV_CTL_ELEM_ACCESS_INACTIVE;
+		}
+
+		snd_ctl_notify(dummy->card, SNDRV_CTL_EVENT_MASK_INFO,
+			       &dummy->cd_volume_ctl->id);
+		snd_ctl_notify(dummy->card, SNDRV_CTL_EVENT_MASK_INFO,
+			       &dummy->cd_switch_ctl->id);
+	}
+
+	return changed;
+}
+
 static struct snd_kcontrol_new snd_dummy_controls[] = {
 DUMMY_VOLUME("Master Volume", 0, MIXER_ADDR_MASTER),
 DUMMY_CAPSRC("Master Capture Switch", 0, MIXER_ADDR_MASTER),
@@ -827,22 +881,37 @@ DUMMY_CAPSRC("Line Capture Switch", 0, MIXER_ADDR_LINE),
 DUMMY_VOLUME("Mic Volume", 0, MIXER_ADDR_MIC),
 DUMMY_CAPSRC("Mic Capture Switch", 0, MIXER_ADDR_MIC),
 DUMMY_VOLUME("CD Volume", 0, MIXER_ADDR_CD),
-DUMMY_CAPSRC("CD Capture Switch", 0, MIXER_ADDR_CD)
+DUMMY_CAPSRC("CD Capture Switch", 0, MIXER_ADDR_CD),
+{
+	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
+	.name  = "External I/O Box",
+	.info  = snd_dummy_iobox_info,
+	.get   = snd_dummy_iobox_get,
+	.put   = snd_dummy_iobox_put,
+},
 };
 
 static int __devinit snd_card_dummy_new_mixer(struct snd_dummy *dummy)
 {
 	struct snd_card *card = dummy->card;
+	struct snd_kcontrol *kcontrol;
 	unsigned int idx;
 	int err;
 
 	spin_lock_init(&dummy->mixer_lock);
 	strcpy(card->mixername, "Dummy Mixer");
+	dummy->iobox = 1;
 
 	for (idx = 0; idx < ARRAY_SIZE(snd_dummy_controls); idx++) {
-		err = snd_ctl_add(card, snd_ctl_new1(&snd_dummy_controls[idx], dummy));
+		kcontrol = snd_ctl_new1(&snd_dummy_controls[idx], dummy);
+		err = snd_ctl_add(card, kcontrol);
 		if (err < 0)
 			return err;
+		if (!strcmp(kcontrol->id.name, "CD Volume"))
+			dummy->cd_volume_ctl = kcontrol;
+		else if (!strcmp(kcontrol->id.name, "CD Capture Switch"))
+			dummy->cd_switch_ctl = kcontrol;
+
 	}
 	return 0;
 }