[ALSA] Fix substream selection in PCM and rawmidi

The PCM and rawmidi substreams can be selected explicitly by opening
control handle and set via *_PREFER_SUBDEVICE ioctl.  But, when
multiple controls are opened, the driver gets confused.
The patch fixes the initialization of prefer_*_subdevice and the
check of multiple controls.  The first set subdevice is picked up
as the valid one.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

1 files changed, 2 insertions, 1 deletions

diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index f52178abf12..ed3b0946956 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -792,7 +792,8 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
                 kctl = snd_ctl_file(list);
                 if (kctl->pid == current->pid) {
                         prefer_subdevice = kctl->prefer_pcm_subdevice;
-                        break;
+                        if (prefer_subdevice != -1)
+                                break;
                 }
         }
         up_read(&card->controls_rwsem);