[PATCH v6 9/9] ALSA: virtio: introduce device suspend/resume support

[Anton Yakovlev]

All running PCM substreams are stopped on device suspend and restarted
on device resume.

Signed-off-by: Anton Yakovlev <anton.yakovlev@xxxxxxxxxxxxxxx>
---
 sound/virtio/virtio_card.c    | 56 +++++++++++++++++++++++++++++++++++
 sound/virtio/virtio_pcm.c     |  1 +
 sound/virtio/virtio_pcm_ops.c | 41 ++++++++++++++++++++-----
 3 files changed, 90 insertions(+), 8 deletions(-)

diff --git a/sound/virtio/virtio_card.c b/sound/virtio/virtio_card.c
index 59455a562018..c7ae8801991d 100644
--- a/sound/virtio/virtio_card.c
+++ b/sound/virtio/virtio_card.c
@@ -323,6 +323,58 @@ static void virtsnd_remove(struct virtio_device *vdev)
 	kfree(snd->event_msgs);
 }
 
+#ifdef CONFIG_PM_SLEEP
+/**
+ * virtsnd_freeze() - Suspend device.
+ * @vdev: VirtIO parent device.
+ *
+ * Context: Any context.
+ * Return: 0 on success, -errno on failure.
+ */
+static int virtsnd_freeze(struct virtio_device *vdev)
+{
+	struct virtio_snd *snd = vdev->priv;
+
+	virtsnd_ctl_msg_cancel_all(snd);
+
+	vdev->config->del_vqs(vdev);
+	vdev->config->reset(vdev);
+
+	kfree(snd->event_msgs);
+
+	/*
+	 * If the virtsnd_restore() fails before re-allocating events, then we
+	 * get a dangling pointer here.
+	 */
+	snd->event_msgs = NULL;
+
+	return 0;
+}
+
+/**
+ * virtsnd_restore() - Resume device.
+ * @vdev: VirtIO parent device.
+ *
+ * Context: Any context.
+ * Return: 0 on success, -errno on failure.
+ */
+static int virtsnd_restore(struct virtio_device *vdev)
+{
+	struct virtio_snd *snd = vdev->priv;
+	int rc;
+
+	rc = virtsnd_find_vqs(snd);
+	if (rc)
+		return rc;
+
+	virtio_device_ready(vdev);
+
+	virtsnd_enable_event_vq(snd);
+
+	return 0;
+}
+#endif /* CONFIG_PM_SLEEP */
+
 static const struct virtio_device_id id_table[] = {
 	{ VIRTIO_ID_SOUND, VIRTIO_DEV_ANY_ID },
 	{ 0 },
@@ -335,6 +387,10 @@ static struct virtio_driver virtsnd_driver = {
 	.validate = virtsnd_validate,
 	.probe = virtsnd_probe,
 	.remove = virtsnd_remove,
+#ifdef CONFIG_PM_SLEEP
+	.freeze = virtsnd_freeze,
+	.restore = virtsnd_restore,
+#endif
 };
 
 static int __init init(void)
diff --git a/sound/virtio/virtio_pcm.c b/sound/virtio/virtio_pcm.c
index 3605151860f2..4a4a6583b002 100644
--- a/sound/virtio/virtio_pcm.c
+++ b/sound/virtio/virtio_pcm.c
@@ -109,6 +109,7 @@ static int virtsnd_pcm_build_hw(struct virtio_pcm_substream *vss,
 		SNDRV_PCM_INFO_BATCH |
 		SNDRV_PCM_INFO_BLOCK_TRANSFER |
 		SNDRV_PCM_INFO_INTERLEAVED |
+		SNDRV_PCM_INFO_RESUME |
 		SNDRV_PCM_INFO_PAUSE;
 
 	if (!info->channels_min || info->channels_min > info->channels_max) {
diff --git a/sound/virtio/virtio_pcm_ops.c b/sound/virtio/virtio_pcm_ops.c
index d02d79bd94f3..03a7e2666cfb 100644
--- a/sound/virtio/virtio_pcm_ops.c
+++ b/sound/virtio/virtio_pcm_ops.c
@@ -167,7 +167,8 @@ static int virtsnd_pcm_hw_params(struct snd_pcm_substream *substream,
 	int vrate = -1;
 	int rc;
 
-	if (virtsnd_pcm_msg_pending_num(vss)) {
+	if (runtime->status->state != SNDRV_PCM_STATE_SUSPENDED &&
+	    virtsnd_pcm_msg_pending_num(vss)) {
 		dev_err(&vdev->dev, "SID %u: invalid I/O queue state\n",
 			vss->sid);
 		return -EBADFD;
@@ -231,6 +232,10 @@ static int virtsnd_pcm_hw_params(struct snd_pcm_substream *substream,
 	if (rc)
 		return rc;
 
+	/* If messages have already been allocated before, do nothing. */
+	if (runtime->status->state == SNDRV_PCM_STATE_SUSPENDED)
+		return 0;
+
 	/* Free previously allocated messages (if any). */
 	virtsnd_pcm_msg_free(vss);
 
@@ -267,20 +272,24 @@ static int virtsnd_pcm_hw_free(struct snd_pcm_substream *substream)
  */
 static int virtsnd_pcm_prepare(struct snd_pcm_substream *substream)
 {
+	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct virtio_pcm_substream *vss = snd_pcm_substream_chip(substream);
 	struct virtio_device *vdev = vss->snd->vdev;
 	struct virtio_snd_msg *msg;
 
-	if (virtsnd_pcm_msg_pending_num(vss)) {
-		dev_err(&vdev->dev, "SID %u: invalid I/O queue state\n",
-			vss->sid);
-		return -EBADFD;
+	if (runtime->status->state != SNDRV_PCM_STATE_SUSPENDED) {
+		if (virtsnd_pcm_msg_pending_num(vss)) {
+			dev_err(&vdev->dev, "SID %u: invalid I/O queue state\n",
+				vss->sid);
+			return -EBADFD;
+		}
+
+		vss->buffer_bytes = snd_pcm_lib_buffer_bytes(substream);
+		vss->hw_ptr = 0;
+		vss->msg_last_enqueued = -1;
 	}
 
-	vss->buffer_bytes = snd_pcm_lib_buffer_bytes(substream);
-	vss->hw_ptr = 0;
 	vss->xfer_xrun = false;
-	vss->msg_last_enqueued = -1;
 	vss->msg_count = 0;
 
 	msg = virtsnd_pcm_ctl_msg_alloc(vss, VIRTIO_SND_R_PCM_PREPARE,
@@ -309,6 +318,21 @@ static int virtsnd_pcm_trigger(struct snd_pcm_substream *substream, int command)
 	int rc;
 
 	switch (command) {
+	case SNDRV_PCM_TRIGGER_RESUME: {
+		/*
+		 * We restart the substream by executing the standard command
+		 * sequence.
+		 */
+		rc = virtsnd_pcm_hw_params(substream, NULL);
+		if (rc)
+			return rc;
+
+		rc = virtsnd_pcm_prepare(substream);
+		if (rc)
+			return rc;
+
+		fallthrough;
+	}
 	case SNDRV_PCM_TRIGGER_START:
 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: {
 		struct virtio_snd_queue *queue = virtsnd_pcm_queue(vss);
@@ -335,6 +359,7 @@ static int virtsnd_pcm_trigger(struct snd_pcm_substream *substream, int command)
 
 		return virtsnd_ctl_msg_send_sync(snd, msg);
 	}
+	case SNDRV_PCM_TRIGGER_SUSPEND:
 	case SNDRV_PCM_TRIGGER_STOP:
 	case SNDRV_PCM_TRIGGER_PAUSE_PUSH: {
 		spin_lock_irqsave(&vss->lock, flags);
-- 
2.30.1