1 files changed, 56 insertions, 12 deletions

diff --git a/sound/core/control.c b/sound/core/control.c
index 9ce00ed20fba..a08ad57c49b6 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