ALSA: compress: fix drain calls blocking other compress functions

commit 917f4b5cba78980a527098a910d94139d3e82c8d upstream.

The drain and drain_notify callback were blocked by low level driver untill the
draining was complete. Due to this being invoked with big fat mutex held, others
ops like reading timestamp, calling pause, drop were blocked.

So to fix this we add a new snd_compr_drain_notify() API. This would be required
to be invoked by low level driver when drain or partial drain has been completed
by the DSP. Thus we make the drain and partial_drain callback as non blocking
and driver returns immediately after notifying DSP.
The waiting is done while relasing the lock so that other ops can go ahead.

Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 38 insertions, 3 deletions

diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
index 5863ba6dd12b..68d3ffcac78b 100644
--- a/sound/core/compress_offload.c
+++ b/sound/core/compress_offload.c
@@ -123,6 +123,7 @@ static int snd_compr_open(struct inode *inode, struct file *f)
 	}
 	runtime->state = SNDRV_PCM_STATE_OPEN;
 	init_waitqueue_head(&runtime->sleep);
+	init_waitqueue_head(&runtime->wait);
 	data->stream.runtime = runtime;
 	f->private_data = (void *)data;
 	mutex_lock(&compr->lock);
@@ -670,12 +671,34 @@ static int snd_compr_stop(struct snd_compr_stream *stream)
 	if (!retval) {
 		stream->runtime->state = SNDRV_PCM_STATE_SETUP;
 		wake_up(&stream->runtime->sleep);
+		snd_compr_drain_notify(stream);
 		stream->runtime->total_bytes_available = 0;
 		stream->runtime->total_bytes_transferred = 0;
 	}
 	return retval;
 }
 
+static int snd_compress_wait_for_drain(struct snd_compr_stream *stream)
+{
+	/*
+	 * We are called with lock held. So drop the lock while we wait for
+	 * drain complete notfication from the driver
+	 *
+	 * It is expected that driver will notify the drain completion and then
+	 * stream will be moved to SETUP state, even if draining resulted in an
+	 * error. We can trigger next track after this.
+	 */
+	stream->runtime->state = SNDRV_PCM_STATE_DRAINING;
+	mutex_unlock(&stream->device->lock);
+
+	wait_event(stream->runtime->wait, stream->runtime->drain_wake);
+
+	wake_up(&stream->runtime->sleep);
+	mutex_lock(&stream->device->lock);
+
+	return 0;
+}
+
 static int snd_compr_drain(struct snd_compr_stream *stream)
 {
 	int retval;
@@ -683,11 +706,17 @@ static int snd_compr_drain(struct snd_compr_stream *stream)
 	if (stream->runtime->state == SNDRV_PCM_STATE_PREPARED ||
 			stream->runtime->state == SNDRV_PCM_STATE_SETUP)
 		return -EPERM;
+
+	stream->runtime->drain_wake = 0;
 	retval = stream->ops->trigger(stream, SND_COMPR_TRIGGER_DRAIN);
-	if (!retval) {
-		stream->runtime->state = SNDRV_PCM_STATE_DRAINING;
+	if (retval) {
+		pr_err("SND_COMPR_TRIGGER_DRAIN failed %d\n", retval);
 		wake_up(&stream->runtime->sleep);
+		return retval;
 	}
+
+	retval = snd_compress_wait_for_drain(stream);
+	stream->runtime->state = SNDRV_PCM_STATE_SETUP;
 	return retval;
 }
 
@@ -723,10 +752,16 @@ static int snd_compr_partial_drain(struct snd_compr_stream *stream)
 	if (stream->next_track == false)
 		return -EPERM;
 
+	stream->runtime->drain_wake = 0;
 	retval = stream->ops->trigger(stream, SND_COMPR_TRIGGER_PARTIAL_DRAIN);
+	if (retval) {
+		pr_err("Partial drain returned failure\n");
+		wake_up(&stream->runtime->sleep);
+		return retval;
+	}
 
 	stream->next_track = false;
-	return retval;
+	return snd_compress_wait_for_drain(stream);
 }
 
 static long snd_compr_ioctl(struct file *f, unsigned int cmd, unsigned long arg)