Added ctl_elem_lock and unlock code...

src/control/control.c

@@ -229,6 +229,30 @@ int snd_ctl_elem_write(snd_ctl_t *ctl, snd_ctl_elem_value_t *control)
 	return ctl->ops->element_write(ctl, control);
 }
 
+/**
+ * \brief Lock CTL element
+ * \param ctl CTL handle
+ * \param control CTL element id pointer
+ * \return 0 on success otherwise a negative error code
+ */
+int snd_ctl_elem_lock(snd_ctl_t *ctl, snd_ctl_elem_id_t *id)
+{
+	assert(ctl && id);
+	return ctl->ops->element_lock(ctl, id);
+}
+
+/**
+ * \brief Unlock CTL element
+ * \param ctl CTL handle
+ * \param control CTL element id pointer
+ * \return 0 on success otherwise a negative error code
+ */
+int snd_ctl_elem_unlock(snd_ctl_t *ctl, snd_ctl_elem_id_t *id)
+{
+	assert(ctl && id);
+	return ctl->ops->element_unlock(ctl, id);
+}
+
 /**
  * \brief Get next hardware dependent device number
  * \param ctl CTL handle

src/control/control_hw.c

@@ -163,6 +163,22 @@ static int snd_ctl_hw_elem_write(snd_ctl_t *handle, snd_ctl_elem_value_t *contro
 	return 0;
 }
 
+static int snd_ctl_hw_elem_lock(snd_ctl_t *handle, snd_ctl_elem_id_t *id)
+{
+	snd_ctl_hw_t *hw = handle->private_data;
+	if (ioctl(hw->fd, SNDRV_CTL_IOCTL_ELEM_LOCK, id) < 0)
+		return -errno;
+	return 0;
+}
+
+static int snd_ctl_hw_elem_unlock(snd_ctl_t *handle, snd_ctl_elem_id_t *id)
+{
+	snd_ctl_hw_t *hw = handle->private_data;
+	if (ioctl(hw->fd, SNDRV_CTL_IOCTL_ELEM_UNLOCK, id) < 0)
+		return -errno;
+	return 0;
+}
+
 static int snd_ctl_hw_hwdep_next_device(snd_ctl_t *handle, int * device)
 {
 	snd_ctl_hw_t *hw = handle->private_data;
@@ -255,6 +271,8 @@ snd_ctl_ops_t snd_ctl_hw_ops = {
 	element_info: snd_ctl_hw_elem_info,
 	element_read: snd_ctl_hw_elem_read,
 	element_write: snd_ctl_hw_elem_write,
+	element_lock: snd_ctl_hw_elem_lock,
+	element_unlock: snd_ctl_hw_elem_unlock,
 	hwdep_next_device: snd_ctl_hw_hwdep_next_device,
 	hwdep_info: snd_ctl_hw_hwdep_info,
 	pcm_next_device: snd_ctl_hw_pcm_next_device,

src/control/control_local.h

@@ -33,6 +33,8 @@ typedef struct _snd_ctl_ops {
 	int (*element_info)(snd_ctl_t *handle, snd_ctl_elem_info_t *info);
 	int (*element_read)(snd_ctl_t *handle, snd_ctl_elem_value_t *control);
 	int (*element_write)(snd_ctl_t *handle, snd_ctl_elem_value_t *control);
+	int (*element_lock)(snd_ctl_t *handle, snd_ctl_elem_id_t *lock);
+	int (*element_unlock)(snd_ctl_t *handle, snd_ctl_elem_id_t *unlock);
 	int (*hwdep_next_device)(snd_ctl_t *handle, int *device);
 	int (*hwdep_info)(snd_ctl_t *handle, snd_hwdep_info_t * info);
 	int (*pcm_next_device)(snd_ctl_t *handle, int *device);

src/control/control_shm.c

@@ -207,6 +207,34 @@ static int snd_ctl_shm_elem_write(snd_ctl_t *ctl, snd_ctl_elem_value_t *control)
 	return err;
 }
 
+static int snd_ctl_shm_elem_lock(snd_ctl_t *ctl, snd_ctl_elem_id_t *id)
+{
+	snd_ctl_shm_t *shm = ctl->private_data;
+	volatile snd_ctl_shm_ctrl_t *ctrl = shm->ctrl;
+	int err;
+	ctrl->u.element_lock = *id;
+	ctrl->cmd = SNDRV_CTL_IOCTL_ELEM_LOCK;
+	err = snd_ctl_shm_action(ctl);
+	if (err < 0)
+		return err;
+	*id = ctrl->u.element_lock;
+	return err;
+}
+
+static int snd_ctl_shm_elem_unlock(snd_ctl_t *ctl, snd_ctl_elem_id_t *id)
+{
+	snd_ctl_shm_t *shm = ctl->private_data;
+	volatile snd_ctl_shm_ctrl_t *ctrl = shm->ctrl;
+	int err;
+	ctrl->u.element_unlock = *id;
+	ctrl->cmd = SNDRV_CTL_IOCTL_ELEM_UNLOCK;
+	err = snd_ctl_shm_action(ctl);
+	if (err < 0)
+		return err;
+	*id = ctrl->u.element_unlock;
+	return err;
+}
+
 static int snd_ctl_shm_hwdep_next_device(snd_ctl_t *ctl, int * device)
 {
 	snd_ctl_shm_t *shm = ctl->private_data;
@@ -362,6 +390,8 @@ snd_ctl_ops_t snd_ctl_shm_ops = {
 	element_info: snd_ctl_shm_elem_info,
 	element_read: snd_ctl_shm_elem_read,
 	element_write: snd_ctl_shm_elem_write,
+	element_lock: snd_ctl_shm_elem_lock,
+	element_unlock: snd_ctl_shm_elem_unlock,
 	hwdep_next_device: snd_ctl_shm_hwdep_next_device,
 	hwdep_info: snd_ctl_shm_hwdep_info,
 	pcm_next_device: snd_ctl_shm_pcm_next_device,