[PATCH 1/2] [ALSA] add SNDRV_PCM_TRIGGER_DRAIN trigger

[libin.yang@intel.com]

From: Libin Yang <libin.yang@intel.com>

Add SNDRV_PCM_TRIGGER_DRAIN trigger for pcm drain.

Some audio devices require notification of drain events
in order to properly drain and shutdown an audio stream.

Signed-off-by: Libin Yang <libin.yang@intel.com>
---
 include/sound/pcm.h     | 1 +
 sound/core/pcm_native.c | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 8bb00a2..bb77aa3 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -109,6 +109,7 @@ struct snd_pcm_ops {
 #define SNDRV_PCM_TRIGGER_PAUSE_RELEASE	4
 #define SNDRV_PCM_TRIGGER_SUSPEND	5
 #define SNDRV_PCM_TRIGGER_RESUME	6
+#define SNDRV_PCM_TRIGGER_DRAIN		7
 
 #define SNDRV_PCM_POS_XRUN		((snd_pcm_uframes_t)-1)
 
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 166d59c..15fe682 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -1517,6 +1517,11 @@ static int snd_pcm_do_drain_init(struct snd_pcm_substream *substream, int state)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+
+		if (substream->runtime->trigger_master == substream)
+			substream->ops->trigger(substream,
+					SNDRV_PCM_TRIGGER_DRAIN);
+
 		switch (runtime->status->state) {
 		case SNDRV_PCM_STATE_PREPARED:
 			/* start playback stream if possible */
-- 
1.9.1