ALSA: usb-audio: Support PCM sync_stop

USB-audio driver had some implementation of its own sync-stop
mechanism.  This patch moved a part of it to the common PCM sync_stop
ops.

Link: https://lore.kernel.org/r/20191210063454.31603-56-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/pcm.c

@@ -260,18 +260,31 @@ static int start_endpoints(struct snd_usb_substream *subs)
 	return 0;
 }
 
-static void stop_endpoints(struct snd_usb_substream *subs, bool wait)
+static void sync_pending_stops(struct snd_usb_substream *subs)
+{
+	snd_usb_endpoint_sync_pending_stop(subs->sync_endpoint);
+	snd_usb_endpoint_sync_pending_stop(subs->data_endpoint);
+}
+
+static void stop_endpoints(struct snd_usb_substream *subs)
 {
 	if (test_and_clear_bit(SUBSTREAM_FLAG_SYNC_EP_STARTED, &subs->flags))
 		snd_usb_endpoint_stop(subs->sync_endpoint);
 
 	if (test_and_clear_bit(SUBSTREAM_FLAG_DATA_EP_STARTED, &subs->flags))
 		snd_usb_endpoint_stop(subs->data_endpoint);
+}
 
-	if (wait) {
-		snd_usb_endpoint_sync_pending_stop(subs->sync_endpoint);
-		snd_usb_endpoint_sync_pending_stop(subs->data_endpoint);
+/* PCM sync_stop callback */
+static int snd_usb_pcm_sync_stop(struct snd_pcm_substream *substream)
+{
+	struct snd_usb_substream *subs = substream->runtime->private_data;
+
+	if (!snd_usb_lock_shutdown(subs->stream->chip)) {
+		sync_pending_stops(subs);
+		snd_usb_unlock_shutdown(subs->stream->chip);
 	}
+	return 0;
 }
 
 static int search_roland_implicit_fb(struct usb_device *dev, int ifnum,
@@ -697,7 +710,8 @@ static int configure_endpoint(struct snd_usb_substream *subs)
 	int ret;
 
 	/* format changed */
-	stop_endpoints(subs, true);
+	stop_endpoints(subs);
+	sync_pending_stops(subs);
 	ret = snd_usb_endpoint_set_params(subs->data_endpoint,
 					  subs->pcm_format,
 					  subs->channels,
@@ -842,7 +856,8 @@ static int snd_usb_hw_free(struct snd_pcm_substream *substream)
 	subs->cur_rate = 0;
 	subs->period_bytes = 0;
 	if (!snd_usb_lock_shutdown(subs->stream->chip)) {
-		stop_endpoints(subs, true);
+		stop_endpoints(subs);
+		sync_pending_stops(subs);
 		snd_usb_endpoint_deactivate(subs->sync_endpoint);
 		snd_usb_endpoint_deactivate(subs->data_endpoint);
 		snd_usb_unlock_shutdown(subs->stream->chip);
@@ -877,9 +892,6 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
 		goto unlock;
 	}
 
-	snd_usb_endpoint_sync_pending_stop(subs->sync_endpoint);
-	snd_usb_endpoint_sync_pending_stop(subs->data_endpoint);
-
 	ret = snd_usb_pcm_change_state(subs, UAC3_PD_STATE_D0);
 	if (ret < 0)
 		goto unlock;
@@ -1337,7 +1349,6 @@ static int snd_usb_pcm_close(struct snd_pcm_substream *substream)
 	struct snd_usb_substream *subs = &as->substream[direction];
 	int ret;
 
-	stop_endpoints(subs, true);
 	snd_media_stop_pipeline(subs);
 
 	if (!as->chip->keep_iface &&
@@ -1714,7 +1725,7 @@ static int snd_usb_substream_playback_trigger(struct snd_pcm_substream *substrea
 		subs->running = 1;
 		return 0;
 	case SNDRV_PCM_TRIGGER_STOP:
-		stop_endpoints(subs, false);
+		stop_endpoints(subs);
 		subs->running = 0;
 		return 0;
 	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
@@ -1744,7 +1755,7 @@ static int snd_usb_substream_capture_trigger(struct snd_pcm_substream *substream
 		subs->running = 1;
 		return 0;
 	case SNDRV_PCM_TRIGGER_STOP:
-		stop_endpoints(subs, false);
+		stop_endpoints(subs);
 		subs->running = 0;
 		return 0;
 	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
@@ -1767,6 +1778,7 @@ static const struct snd_pcm_ops snd_usb_playback_ops = {
 	.hw_free =	snd_usb_hw_free,
 	.prepare =	snd_usb_pcm_prepare,
 	.trigger =	snd_usb_substream_playback_trigger,
+	.sync_stop =	snd_usb_pcm_sync_stop,
 	.pointer =	snd_usb_pcm_pointer,
 };
 
@@ -1777,6 +1789,7 @@ static const struct snd_pcm_ops snd_usb_capture_ops = {
 	.hw_free =	snd_usb_hw_free,
 	.prepare =	snd_usb_pcm_prepare,
 	.trigger =	snd_usb_substream_capture_trigger,
+	.sync_stop =	snd_usb_pcm_sync_stop,
 	.pointer =	snd_usb_pcm_pointer,
 };