1 files changed, 56 insertions, 12 deletions

diff --git a/sound/core/control.c b/sound/core/control.c
index 9ce00ed20fb..a08ad57c49b 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -279,33 +279,31 @@ void snd_ctl_free_one(struct snd_kcontrol *kcontrol)
 
 EXPORT_SYMBOL(snd_ctl_free_one);
 
-static unsigned int snd_ctl_hole_check(struct snd_card *card,
-				       unsigned int count)
+static bool snd_ctl_remove_numid_conflict(struct snd_card *card,
+					  unsigned int count)
 {
 	struct snd_kcontrol *kctl;
 
 	list_for_each_entry(kctl, &card->controls, list) {
-		if ((kctl->id.numid <= card->last_numid &&
-		     kctl->id.numid + kctl->count > card->last_numid) ||
-		    (kctl->id.numid <= card->last_numid + count - 1 &&
-		     kctl->id.numid + kctl->count > card->last_numid + count - 1))
-		    	return card->last_numid = kctl->id.numid + kctl->count - 1;
+		if (kctl->id.numid < card->last_numid + 1 + count &&
+		    kctl->id.numid + kctl->count > card->last_numid + 1) {
+		    	card->last_numid = kctl->id.numid + kctl->count - 1;
+			return true;
+		}
 	}
-	return card->last_numid;
+	return false;
 }
 
 static int snd_ctl_find_hole(struct snd_card *card, unsigned int count)
 {
-	unsigned int last_numid, iter = 100000;
+	unsigned int iter = 100000;
 
-	last_numid = card->last_numid;
-	while (last_numid != snd_ctl_hole_check(card, count)) {
+	while (snd_ctl_remove_numid_conflict(card, count)) {
 		if (--iter == 0) {
 			/* this situation is very unlikely */
 			snd_printk(KERN_ERR "unable to allocate new control numid\n");
 			return -ENOMEM;
 		}
-		last_numid = card->last_numid;
 	}
 	return 0;
 }
@@ -466,6 +464,52 @@ error:
 }
 
 /**
+ * snd_ctl_activate_id - activate/inactivate the control of the given id
+ * @card: the card instance
+ * @id: the control id to activate/inactivate
+ * @active: non-zero to activate
+ *
+ * Finds the control instance with the given id, and activate or
+ * inactivate the control together with notification, if changed.
+ *
+ * Returns 0 if unchanged, 1 if changed, or a negative error code on failure.
+ */
+int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id,
+			int active)
+{
+	struct snd_kcontrol *kctl;
+	struct snd_kcontrol_volatile *vd;
+	unsigned int index_offset;
+	int ret;
+
+	down_write(&card->controls_rwsem);
+	kctl = snd_ctl_find_id(card, id);
+	if (kctl == NULL) {
+		ret = -ENOENT;
+		goto unlock;
+	}
+	index_offset = snd_ctl_get_ioff(kctl, &kctl->id);
+	vd = &kctl->vd[index_offset];
+	ret = 0;
+	if (active) {
+		if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE))
+			goto unlock;
+		vd->access &= ~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
+	} else {
+		if (vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE)
+			goto unlock;
+		vd->access |= SNDRV_CTL_ELEM_ACCESS_INACTIVE;
+	}
+	ret = 1;
+ unlock:
+	up_write(&card->controls_rwsem);
+	if (ret > 0)
+		snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO, id);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(snd_ctl_activate_id);
+
+/**
  * snd_ctl_rename_id - replace the id of a control on the card
  * @card: the card instance
  * @src_id: the old id