diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 67a4d6d..4f49ca7 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -67,6 +67,8 @@
 	unsigned int hwptr_done;
 
 	subs = (struct snd_usb_substream *)substream->runtime->private_data;
+	if (subs->stream->chip->shutdown)
+		return SNDRV_PCM_POS_XRUN;
 	spin_lock(&subs->lock);
 	hwptr_done = subs->hwptr_done;
 	substream->runtime->delay = snd_usb_pcm_delay(subs,
@@ -373,8 +375,14 @@
 	changed = subs->cur_audiofmt != fmt ||
 		subs->period_bytes != params_period_bytes(hw_params) ||
 		subs->cur_rate != rate;
+
+	mutex_lock(&subs->stream->chip->shutdown_mutex);
+	if (subs->stream->chip->shutdown) {
+		ret = -ENODEV;
+		goto unlock;
+	}
 	if ((ret = set_format(subs, fmt)) < 0)
-		return ret;
+		goto unlock;
 
 	if (subs->cur_rate != rate) {
 		struct usb_host_interface *alts;
@@ -383,12 +391,11 @@
 		alts = &iface->altsetting[fmt->altset_idx];
 		ret = snd_usb_init_sample_rate(subs->stream->chip, subs->interface, alts, fmt, rate);
 		if (ret < 0)
-			return ret;
+			goto unlock;
 		subs->cur_rate = rate;
 	}
 
 	if (changed) {
-		mutex_lock(&subs->stream->chip->shutdown_mutex);
 		/* format changed */
 		snd_usb_release_substream_urbs(subs, 0);
 		/* influenced: period_bytes, channels, rate, format, */
@@ -396,9 +403,10 @@
 						  params_rate(hw_params),
 						  snd_pcm_format_physical_width(params_format(hw_params)) *
 							params_channels(hw_params));
-		mutex_unlock(&subs->stream->chip->shutdown_mutex);
 	}
 
+unlock:
+	mutex_unlock(&subs->stream->chip->shutdown_mutex);
 	return ret;
 }
 
@@ -429,12 +437,18 @@
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct snd_usb_substream *subs = runtime->private_data;
+	int ret = 0;
 
 	if (! subs->cur_audiofmt) {
 		snd_printk(KERN_ERR "usbaudio: no format is specified!\n");
 		return -ENXIO;
 	}
 
+	mutex_lock(&subs->stream->chip->shutdown_mutex);
+	if (subs->stream->chip->shutdown) {
+		ret = -ENODEV;
+		goto unlock;
+	}
 	/* some unit conversions in runtime */
 	subs->maxframesize = bytes_to_frames(runtime, subs->maxpacksize);
 	subs->curframesize = bytes_to_frames(runtime, subs->curpacksize);
@@ -447,7 +461,10 @@
 	subs->last_frame_number = 0;
 	runtime->delay = 0;
 
-	return snd_usb_substream_prepare(subs, runtime);
+	ret = snd_usb_substream_prepare(subs, runtime);
+ unlock:
+	mutex_unlock(&subs->stream->chip->shutdown_mutex);
+	return ret;
 }
 
 static struct snd_pcm_hardware snd_usb_hardware =
@@ -500,7 +517,7 @@
 		return 0;
 	}
 	/* check whether the period time is >= the data packet interval */
-	if (snd_usb_get_speed(subs->dev) != USB_SPEED_FULL) {
+	if (subs->speed != USB_SPEED_FULL) {
 		ptime = 125 * (1 << fp->datainterval);
 		if (ptime > pt->max || (ptime == pt->max && pt->openmax)) {
 			hwc_debug("   > check: ptime %u > max %u\n", ptime, pt->max);
@@ -778,7 +795,7 @@
 		return err;
 
 	param_period_time_if_needed = SNDRV_PCM_HW_PARAM_PERIOD_TIME;
-	if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL)
+	if (subs->speed == USB_SPEED_FULL)
 		/* full speed devices have fixed data packet interval */
 		ptmin = 1000;
 	if (ptmin == 1000)