Revert "ALSA: usb-audio: Split endpoint setups for hw_params and prepare (take#2)"

This reverts commit 56e28371fa which is
commit 2be79d5864 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: Ia50296da98428649613548dfe31c8dc9669da0d6
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

sound/usb/endpoint.c

@@ -42,7 +42,6 @@ struct snd_usb_clock_ref {
 	unsigned char clock;
 	atomic_t locked;
 	int rate;
-	bool need_setup;
 	struct list_head list;
 };
 
@@ -768,8 +767,7 @@ bool snd_usb_endpoint_compatible(struct snd_usb_audio *chip,
  * The endpoint needs to be closed via snd_usb_endpoint_close() later.
  *
  * Note that this function doesn't configure the endpoint.  The substream
- * needs to set it up later via snd_usb_endpoint_set_params() and
- * snd_usb_endpoint_prepare().
+ * needs to set it up later via snd_usb_endpoint_configure().
  */
 struct snd_usb_endpoint *
 snd_usb_endpoint_open(struct snd_usb_audio *chip,
@@ -1302,39 +1300,15 @@ out_of_memory:
 	return -ENOMEM;
 }
 
-/* update the rate of the referred clock; return the actual rate */
-static int update_clock_ref_rate(struct snd_usb_audio *chip,
-				 struct snd_usb_endpoint *ep)
-{
-	struct snd_usb_clock_ref *clock = ep->clock_ref;
-	int rate = ep->cur_rate;
-
-	if (!clock || clock->rate == rate)
-		return rate;
-	if (clock->rate) {
-		if (atomic_read(&clock->locked))
-			return clock->rate;
-		if (clock->rate != rate) {
-			usb_audio_err(chip, "Mismatched sample rate %d vs %d for EP 0x%x\n",
-				      clock->rate, rate, ep->ep_num);
-			return clock->rate;
-		}
-	}
-	clock->rate = rate;
-	clock->need_setup = true;
-	return rate;
-}
-
 /*
  * snd_usb_endpoint_set_params: configure an snd_usb_endpoint
  *
- * It's called either from hw_params callback.
  * Determine the number of URBs to be used on this endpoint.
  * An endpoint must be configured before it can be started.
  * An endpoint that is already running can not be reconfigured.
  */
-int snd_usb_endpoint_set_params(struct snd_usb_audio *chip,
-				struct snd_usb_endpoint *ep)
+static int snd_usb_endpoint_set_params(struct snd_usb_audio *chip,
+				       struct snd_usb_endpoint *ep)
 {
 	const struct audioformat *fmt = ep->cur_audiofmt;
 	int err;
@@ -1386,46 +1360,49 @@ int snd_usb_endpoint_set_params(struct snd_usb_audio *chip,
 	ep->maxframesize = ep->maxpacksize / ep->cur_frame_bytes;
 	ep->curframesize = ep->curpacksize / ep->cur_frame_bytes;
 
-	return update_clock_ref_rate(chip, ep);
+	return 0;
 }
 
 static int init_sample_rate(struct snd_usb_audio *chip,
 			    struct snd_usb_endpoint *ep)
 {
 	struct snd_usb_clock_ref *clock = ep->clock_ref;
-	int rate, err;
+	int err;
 
-	rate = update_clock_ref_rate(chip, ep);
-	if (rate < 0)
-		return rate;
-	if (clock && !clock->need_setup)
-		return 0;
-
-	err = snd_usb_init_sample_rate(chip, ep->cur_audiofmt, rate);
-	if (err < 0) {
-		if (clock)
-			clock->rate = 0; /* reset rate */
-		return err;
+	if (clock) {
+		if (atomic_read(&clock->locked))
+			return 0;
+		if (clock->rate == ep->cur_rate)
+			return 0;
+		if (clock->rate && clock->rate != ep->cur_rate) {
+			usb_audio_dbg(chip, "Mismatched sample rate %d vs %d for EP 0x%x\n",
+				      clock->rate, ep->cur_rate, ep->ep_num);
+			return -EINVAL;
+		}
 	}
 
+	err = snd_usb_init_sample_rate(chip, ep->cur_audiofmt, ep->cur_rate);
+	if (err < 0)
+		return err;
+
 	if (clock)
-		clock->need_setup = false;
+		clock->rate = ep->cur_rate;
 	return 0;
 }
 
 /*
- * snd_usb_endpoint_prepare: Prepare the endpoint
+ * snd_usb_endpoint_configure: Configure the endpoint
  *
  * This function sets up the EP to be fully usable state.
- * It's called either from prepare callback.
+ * It's called either from hw_params or prepare callback.
  * The function checks need_setup flag, and performs nothing unless needed,
  * so it's safe to call this multiple times.
  *
  * This returns zero if unchanged, 1 if the configuration has changed,
  * or a negative error code.
  */
-int snd_usb_endpoint_prepare(struct snd_usb_audio *chip,
-			     struct snd_usb_endpoint *ep)
+int snd_usb_endpoint_configure(struct snd_usb_audio *chip,
+			       struct snd_usb_endpoint *ep)
 {
 	bool iface_first;
 	int err = 0;
@@ -1446,6 +1423,9 @@ int snd_usb_endpoint_prepare(struct snd_usb_audio *chip,
 			if (err < 0)
 				goto unlock;
 		}
+		err = snd_usb_endpoint_set_params(chip, ep);
+		if (err < 0)
+			goto unlock;
 		goto done;
 	}
 
@@ -1473,6 +1453,10 @@ int snd_usb_endpoint_prepare(struct snd_usb_audio *chip,
 	if (err < 0)
 		goto unlock;
 
+	err = snd_usb_endpoint_set_params(chip, ep);
+	if (err < 0)
+		goto unlock;
+
 	err = snd_usb_select_mode_quirk(chip, ep->cur_audiofmt);
 	if (err < 0)
 		goto unlock;

sound/usb/endpoint.h

@@ -17,10 +17,8 @@ snd_usb_endpoint_open(struct snd_usb_audio *chip,
 		      bool is_sync_ep);
 void snd_usb_endpoint_close(struct snd_usb_audio *chip,
 			    struct snd_usb_endpoint *ep);
-int snd_usb_endpoint_set_params(struct snd_usb_audio *chip,
-				struct snd_usb_endpoint *ep);
-int snd_usb_endpoint_prepare(struct snd_usb_audio *chip,
-			     struct snd_usb_endpoint *ep);
+int snd_usb_endpoint_configure(struct snd_usb_audio *chip,
+			       struct snd_usb_endpoint *ep);
 int snd_usb_endpoint_get_clock_rate(struct snd_usb_audio *chip, int clock);
 
 bool snd_usb_endpoint_compatible(struct snd_usb_audio *chip,

sound/usb/pcm.c

@@ -442,6 +442,35 @@ static void close_endpoints(struct snd_usb_audio *chip,
 	}
 }
 
+static int configure_endpoints(struct snd_usb_audio *chip,
+			       struct snd_usb_substream *subs)
+{
+	int err;
+
+	if (subs->data_endpoint->need_setup) {
+		/* stop any running stream beforehand */
+		if (stop_endpoints(subs, false))
+			sync_pending_stops(subs);
+		if (subs->sync_endpoint) {
+			err = snd_usb_endpoint_configure(chip, subs->sync_endpoint);
+			if (err < 0)
+				return err;
+		}
+		err = snd_usb_endpoint_configure(chip, subs->data_endpoint);
+		if (err < 0)
+			return err;
+		snd_usb_set_format_quirk(subs, subs->cur_audiofmt);
+	} else {
+		if (subs->sync_endpoint) {
+			err = snd_usb_endpoint_configure(chip, subs->sync_endpoint);
+			if (err < 0)
+				return err;
+		}
+	}
+
+	return 0;
+}
+
 /*
  * hw_params callback
  *
@@ -533,16 +562,7 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
 	subs->cur_audiofmt = fmt;
 	mutex_unlock(&chip->mutex);
 
-	if (!subs->data_endpoint->need_setup)
-		goto unlock;
-
-	if (subs->sync_endpoint) {
-		ret = snd_usb_endpoint_set_params(chip, subs->sync_endpoint);
-		if (ret < 0)
-			goto unlock;
-	}
-
-	ret = snd_usb_endpoint_set_params(chip, subs->data_endpoint);
+	ret = configure_endpoints(chip, subs);
 
  unlock:
 	if (ret < 0)
@@ -625,18 +645,9 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
 		goto unlock;
 	}
 
-	if (subs->sync_endpoint) {
-		ret = snd_usb_endpoint_prepare(chip, subs->sync_endpoint);
-		if (ret < 0)
-			goto unlock;
-	}
-
-	ret = snd_usb_endpoint_prepare(chip, subs->data_endpoint);
+	ret = configure_endpoints(chip, subs);
 	if (ret < 0)
 		goto unlock;
-	else if (ret > 0)
-		snd_usb_set_format_quirk(subs, subs->cur_audiofmt);
-	ret = 0;
 
 	/* reset the pointer */
 	subs->buffer_bytes = frames_to_bytes(runtime, runtime->buffer_size);