diff --git a/sound/usb/card.c b/sound/usb/card.c
index 4a52dd99bea1..f6195e8e4633 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -225,72 +225,6 @@ static int snd_vendor_usb_add_ctls(struct snd_usb_audio *chip)
 	return 0;
 }
 
-struct snd_usb_substream *find_snd_usb_substream(unsigned int card_num,
-	unsigned int pcm_idx, unsigned int direction, struct snd_usb_audio
-	**uchip, void (*disconnect_cb)(struct snd_usb_audio *chip))
-{
-	int idx;
-	struct snd_usb_stream *as;
-	struct snd_usb_substream *subs = NULL;
-	struct snd_usb_audio *chip = NULL;
-
-	mutex_lock(&register_mutex);
-	/*
-	 * legacy audio snd card number assignment is dynamic. Hence
-	 * search using chip->card->number
-	 */
-	for (idx = 0; idx < SNDRV_CARDS; idx++) {
-		if (!usb_chip[idx])
-			continue;
-		if (usb_chip[idx]->card->number == card_num) {
-			chip = usb_chip[idx];
-			break;
-		}
-	}
-
-	if (!chip || atomic_read(&chip->shutdown)) {
-		pr_debug("%s: instance of usb crad # %d does not exist\n",
-			__func__, card_num);
-		goto err;
-	}
-
-	if (pcm_idx >= chip->pcm_devs) {
-		pr_err("%s: invalid pcm dev number %u > %d\n", __func__,
-			pcm_idx, chip->pcm_devs);
-		goto err;
-	}
-
-	if (direction > SNDRV_PCM_STREAM_CAPTURE) {
-		pr_err("%s: invalid direction %u\n", __func__, direction);
-		goto err;
-	}
-
-	list_for_each_entry(as, &chip->pcm_list, list) {
-		if (as->pcm_index == pcm_idx) {
-			subs = &as->substream[direction];
-			if (subs->interface < 0 && !subs->data_endpoint &&
-				!subs->sync_endpoint) {
-				pr_debug("%s: stream disconnected, bail out\n",
-					__func__);
-				subs = NULL;
-				goto err;
-			}
-			goto done;
-		}
-	}
-
-done:
-	chip->card_num = card_num;
-	chip->disconnect_cb = disconnect_cb;
-err:
-	*uchip = chip;
-	if (!subs)
-		pr_debug("%s: substream instance not found\n", __func__);
-	mutex_unlock(&register_mutex);
-	return subs;
-}
-EXPORT_SYMBOL_GPL(find_snd_usb_substream);
-
 /*
  * disconnect streams
  * called from usb_audio_disconnect()
@@ -630,7 +564,6 @@ static void snd_usb_audio_free(struct snd_card *card)
 	list_for_each_entry_safe(ep, n, &chip->ep_list, list)
 		snd_usb_endpoint_free(ep);
 
-	mutex_destroy(&chip->dev_lock);
 	mutex_destroy(&chip->mutex);
 	if (!atomic_read(&chip->shutdown))
 		dev_set_drvdata(&chip->dev->dev, NULL);
@@ -773,7 +706,6 @@ static int snd_usb_audio_create(struct usb_interface *intf,
 
 	chip = card->private_data;
 	mutex_init(&chip->mutex);
-	mutex_init(&chip->dev_lock);
 	init_waitqueue_head(&chip->shutdown_wait);
 	chip->index = idx;
 	chip->dev = dev;
@@ -1050,9 +982,6 @@ static void usb_audio_disconnect(struct usb_interface *intf)
 
 	card = chip->card;
 
-	if (chip->disconnect_cb)
-		chip->disconnect_cb(chip);
-
 	snd_vendor_disconnect(intf);
 
 	mutex_lock(&register_mutex);
diff --git a/sound/usb/card.h b/sound/usb/card.h
index ce4f213d5cf5..a5d61cd160d5 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -182,10 +182,6 @@ struct snd_usb_stream {
 	struct list_head list;
 };
 
-struct snd_usb_substream *find_snd_usb_substream(unsigned int card_num,
-	unsigned int pcm_idx, unsigned int direction, struct snd_usb_audio
-	**uchip, void (*disconnect_cb)(struct snd_usb_audio *chip));
-
 int snd_vendor_set_ops(struct snd_usb_audio_vendor_ops *vendor_ops);
 struct snd_usb_audio_vendor_ops *snd_vendor_get_ops(void);
 int snd_vendor_set_interface(struct usb_device *udev,
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 947b2c23dc68..30d12718c6c9 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -140,69 +140,6 @@ static struct audioformat *find_format(struct snd_usb_substream *subs)
 	return found;
 }
 
-/*
- * find a matching audio format as well as non-zero service interval
- */
-static struct audioformat *find_format_and_si(struct snd_usb_substream *subs,
-	unsigned int datainterval)
-{
-	unsigned int i;
-	struct audioformat *fp;
-	struct audioformat *found = NULL;
-	int cur_attr = 0, attr;
-
-	list_for_each_entry(fp, &subs->fmt_list, list) {
-		if (datainterval != fp->datainterval)
-			continue;
-		if (!(fp->formats & pcm_format_to_bits(subs->pcm_format)))
-			continue;
-		if (fp->channels != subs->channels)
-			continue;
-		if (subs->cur_rate < fp->rate_min ||
-		    subs->cur_rate > fp->rate_max)
-			continue;
-		if (!(fp->rates & SNDRV_PCM_RATE_CONTINUOUS)) {
-			for (i = 0; i < fp->nr_rates; i++)
-				if (fp->rate_table[i] == subs->cur_rate)
-					break;
-			if (i >= fp->nr_rates)
-				continue;
-		}
-		attr = fp->ep_attr & USB_ENDPOINT_SYNCTYPE;
-		if (!found) {
-			found = fp;
-			cur_attr = attr;
-			continue;
-		}
-		/* avoid async out and adaptive in if the other method
-		 * supports the same format.
-		 * this is a workaround for the case like
-		 * M-audio audiophile USB.
-		 */
-		if (attr != cur_attr) {
-			if ((attr == USB_ENDPOINT_SYNC_ASYNC &&
-			     subs->direction == SNDRV_PCM_STREAM_PLAYBACK) ||
-			    (attr == USB_ENDPOINT_SYNC_ADAPTIVE &&
-			     subs->direction == SNDRV_PCM_STREAM_CAPTURE))
-				continue;
-			if ((cur_attr == USB_ENDPOINT_SYNC_ASYNC &&
-			     subs->direction == SNDRV_PCM_STREAM_PLAYBACK) ||
-			    (cur_attr == USB_ENDPOINT_SYNC_ADAPTIVE &&
-			     subs->direction == SNDRV_PCM_STREAM_CAPTURE)) {
-				found = fp;
-				cur_attr = attr;
-				continue;
-			}
-		}
-		/* find the format with the largest max. packet size */
-		if (fp->maxpacksize > found->maxpacksize) {
-			found = fp;
-			cur_attr = attr;
-		}
-	}
-	return found;
-}
-
 static int init_pitch_v1(struct snd_usb_audio *chip, int iface,
 			 struct usb_host_interface *alts,
 			 struct audioformat *fmt)
@@ -684,81 +621,6 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
 	return 0;
 }
 
-static int snd_usb_pcm_change_state(struct snd_usb_substream *subs, int state);
-
-int snd_usb_enable_audio_stream(struct snd_usb_substream *subs,
-	int datainterval, bool enable)
-{
-	struct audioformat *fmt;
-	struct usb_host_interface *alts;
-	struct usb_interface *iface;
-	int ret;
-
-	if (!enable) {
-		if (subs->interface >= 0) {
-			usb_set_interface(subs->dev, subs->interface, 0);
-			subs->altset_idx = 0;
-			subs->interface = -1;
-			subs->cur_audiofmt = NULL;
-		}
-
-		snd_usb_autosuspend(subs->stream->chip);
-		return 0;
-	}
-
-	snd_usb_autoresume(subs->stream->chip);
-
-	ret = snd_usb_pcm_change_state(subs, UAC3_PD_STATE_D0);
-	if (ret < 0)
-		return ret;
-
-	if (datainterval != -EINVAL)
-		fmt = find_format_and_si(subs, datainterval);
-	else
-		fmt = find_format(subs);
-	if (!fmt) {
-		dev_err(&subs->dev->dev,
-		"cannot set format: format = %#x, rate = %d, channels = %d\n",
-			   subs->pcm_format, subs->cur_rate, subs->channels);
-		return -EINVAL;
-	}
-
-	subs->altset_idx = 0;
-	subs->interface = -1;
-	if (atomic_read(&subs->stream->chip->shutdown)) {
-		ret = -ENODEV;
-	} else {
-		ret = set_format(subs, fmt);
-		if (ret < 0)
-			return ret;
-
-		iface = usb_ifnum_to_if(subs->dev, subs->cur_audiofmt->iface);
-		if (!iface) {
-			dev_err(&subs->dev->dev, "Could not get iface %d\n",
-				subs->cur_audiofmt->iface);
-			return -ENODEV;
-		}
-
-		alts = &iface->altsetting[subs->cur_audiofmt->altset_idx];
-		ret = snd_usb_init_sample_rate(subs->stream->chip,
-					       subs->cur_audiofmt->iface,
-					       alts,
-					       subs->cur_audiofmt,
-					       subs->cur_rate);
-		if (ret < 0) {
-			dev_err(&subs->dev->dev, "failed to set rate %d\n",
-				subs->cur_rate);
-			return ret;
-		}
-	}
-
-	subs->interface = fmt->iface;
-	subs->altset_idx = fmt->altset_idx;
-
-	return 0;
-}
-EXPORT_SYMBOL_GPL(snd_usb_enable_audio_stream);
-
 /*
  * Return the score of matching two audioformats.
  * Veto the audioformat if:
diff --git a/sound/usb/pcm.h b/sound/usb/pcm.h
index 6e28e791e761..9833627c1eca 100644
--- a/sound/usb/pcm.h
+++ b/sound/usb/pcm.h
@@ -14,7 +14,5 @@ int snd_usb_init_pitch(struct snd_usb_audio *chip, int iface,
 		       struct audioformat *fmt);
 void snd_usb_preallocate_buffer(struct snd_usb_substream *subs);
 
-int snd_usb_enable_audio_stream(struct snd_usb_substream *subs,
-				int datainterval, bool enable);
 
 #endif /* __USBAUDIO_PCM_H */
diff --git a/sound/usb/stream.c b/sound/usb/stream.c
index 7ff203dc3cec..ca76ba5b5c0b 100644
--- a/sound/usb/stream.c
+++ b/sound/usb/stream.c
@@ -67,13 +67,9 @@ static void snd_usb_audio_stream_free(struct snd_usb_stream *stream)
 static void snd_usb_audio_pcm_free(struct snd_pcm *pcm)
 {
 	struct snd_usb_stream *stream = pcm->private_data;
-	struct snd_usb_audio *chip;
 	if (stream) {
-		mutex_lock(&stream->chip->dev_lock);
-		chip = stream->chip;
 		stream->pcm = NULL;
 		snd_usb_audio_stream_free(stream);
-		mutex_unlock(&chip->dev_lock);
 	}
 }
 
diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index 9b3946a0f3a8..be6e1cba7c41 100644
--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -60,9 +60,6 @@ struct snd_usb_audio {
 	struct usb_host_interface *ctrl_intf;	/* the audio control interface */
 	struct media_device *media_dev;
 	struct media_intf_devnode *ctl_intf_media_devnode;
-	struct mutex dev_lock;  /* to protect any race with disconnect */
-	int card_num;	/* cache pcm card number to use upon disconnect */
-	void (*disconnect_cb)(struct snd_usb_audio *chip);
 };
 
 #define usb_audio_err(chip, fmt, args...) \