ALSA: control: Provide a helper to look for the preferred subdevice

[mirror_ubuntu-zesty-kernel.git] / sound / core / control.c

diff --git a/sound/core/control.c b/sound/core/control.c
index bb96a467e88d080ff693766f77b36b4dc1a02b01..cd246a0bcd5528e7302c2c0ea69e63482da177c1 100644 (file)
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -50,7 +50,7 @@ static int snd_ctl_open(struct inode *inode, struct file *file)
        unsigned long flags;
        struct snd_card *card;
        struct snd_ctl_file *ctl;
-       int err;
+       int i, err;
 
        err = nonseekable_open(inode, file);
        if (err < 0)
@@ -79,8 +79,8 @@ static int snd_ctl_open(struct inode *inode, struct file *file)
        init_waitqueue_head(&ctl->change_sleep);
        spin_lock_init(&ctl->read_lock);
        ctl->card = card;
-       ctl->prefer_pcm_subdevice = -1;
-       ctl->prefer_rawmidi_subdevice = -1;
+       for (i = 0; i < SND_CTL_SUBDEV_ITEMS; i++)
+               ctl->preferred_subdevice[i] = -1;
        ctl->pid = get_pid(task_pid(current));
        file->private_data = ctl;
        write_lock_irqsave(&card->ctl_files_rwlock, flags);
@@ -1607,6 +1607,27 @@ static int snd_ctl_fasync(int fd, struct file * file, int on)
        return fasync_helper(fd, file, on, &ctl->fasync);
 }
 
+/* return the preferred subdevice number if already assigned;
+ * otherwise return -1
+ */
+int snd_ctl_get_preferred_subdevice(struct snd_card *card, int type)
+{
+       struct snd_ctl_file *kctl;
+       int subdevice = -1;
+
+       read_lock(&card->ctl_files_rwlock);
+       list_for_each_entry(kctl, &card->ctl_files, list) {
+               if (kctl->pid == task_pid(current)) {
+                       subdevice = kctl->preferred_subdevice[type];
+                       if (subdevice != -1)
+                               break;
+               }
+       }
+       read_unlock(&card->ctl_files_rwlock);
+       return subdevice;
+}
+EXPORT_SYMBOL_GPL(snd_ctl_get_preferred_subdevice);
+
 /*
  * ioctl32 compat
  */