diff --git a/drivers/staging/line6/capture.c b/drivers/staging/line6/capture.c
index 127f9524774..c85c5b6bffb 100644
--- a/drivers/staging/line6/capture.c
+++ b/drivers/staging/line6/capture.c
@@ -107,7 +107,7 @@ void line6_unlink_audio_in_urbs(struct snd_line6_pcm *line6pcm)
 	Wait until unlinking of all currently active capture URBs has been
 	finished.
 */
-static void wait_clear_audio_in_urbs(struct snd_line6_pcm *line6pcm)
+void line6_wait_clear_audio_in_urbs(struct snd_line6_pcm *line6pcm)
 {
 	int timeout = HZ;
 	unsigned int i;
@@ -134,7 +134,7 @@ static void wait_clear_audio_in_urbs(struct snd_line6_pcm *line6pcm)
 void line6_unlink_wait_clear_audio_in_urbs(struct snd_line6_pcm *line6pcm)
 {
 	line6_unlink_audio_in_urbs(line6pcm);
-	wait_clear_audio_in_urbs(line6pcm);
+	line6_wait_clear_audio_in_urbs(line6pcm);
 }
 
 /*
@@ -193,25 +193,6 @@ void line6_capture_check_period(struct snd_line6_pcm *line6pcm, int length)
 	}
 }
 
-int line6_alloc_capture_buffer(struct snd_line6_pcm *line6pcm)
-{
-	/* We may be invoked multiple times in a row so allocate once only */
-	if (line6pcm->buffer_in)
-		return 0;
-
-	line6pcm->buffer_in =
-		kmalloc(LINE6_ISO_BUFFERS * LINE6_ISO_PACKETS *
-			line6pcm->max_packet_size, GFP_KERNEL);
-
-	if (!line6pcm->buffer_in) {
-		dev_err(line6pcm->line6->ifcdev,
-			"cannot malloc capture buffer\n");
-		return -ENOMEM;
-	}
-
-	return 0;
-}
-
 void line6_free_capture_buffer(struct snd_line6_pcm *line6pcm)
 {
 	kfree(line6pcm->buffer_in);
@@ -273,9 +254,9 @@ static void audio_in_callback(struct urb *urb)
 		line6pcm->prev_fsize = fsize;
 
 #ifdef CONFIG_LINE6_USB_IMPULSE_RESPONSE
-		if (!(line6pcm->flags & MASK_PCM_IMPULSE))
+		if (!(line6pcm->flags & LINE6_BITS_PCM_IMPULSE))
 #endif
-			if (test_bit(BIT_PCM_ALSA_CAPTURE, &line6pcm->flags)
+			if (test_bit(LINE6_INDEX_PCM_ALSA_CAPTURE_STREAM, &line6pcm->flags)
 			    && (fsize > 0))
 				line6_capture_copy(line6pcm, fbuf, fsize);
 	}
@@ -291,9 +272,9 @@ static void audio_in_callback(struct urb *urb)
 		submit_audio_in_urb(line6pcm);
 
 #ifdef CONFIG_LINE6_USB_IMPULSE_RESPONSE
-		if (!(line6pcm->flags & MASK_PCM_IMPULSE))
+		if (!(line6pcm->flags & LINE6_BITS_PCM_IMPULSE))
 #endif
-			if (test_bit(BIT_PCM_ALSA_CAPTURE, &line6pcm->flags))
+			if (test_bit(LINE6_INDEX_PCM_ALSA_CAPTURE_STREAM, &line6pcm->flags))
 				line6_capture_check_period(line6pcm, length);
 	}
 }
@@ -341,17 +322,17 @@ static int snd_line6_capture_hw_params(struct snd_pcm_substream *substream,
 	}
 	/* -- [FD] end */
 
-	if ((line6pcm->flags & MASK_CAPTURE) == 0) {
-		ret = line6_alloc_capture_buffer(line6pcm);
+	ret = line6_pcm_acquire(line6pcm, LINE6_BIT_PCM_ALSA_CAPTURE_BUFFER);
 
-		if (ret < 0)
-			return ret;
-	}
+	if (ret < 0)
+		return ret;
 
 	ret = snd_pcm_lib_malloc_pages(substream,
 				       params_buffer_bytes(hw_params));
-	if (ret < 0)
+	if (ret < 0) {
+		line6_pcm_release(line6pcm, LINE6_BIT_PCM_ALSA_CAPTURE_BUFFER);
 		return ret;
+	}
 
 	line6pcm->period_in = params_period_bytes(hw_params);
 	return 0;
@@ -361,12 +342,7 @@ static int snd_line6_capture_hw_params(struct snd_pcm_substream *substream,
 static int snd_line6_capture_hw_free(struct snd_pcm_substream *substream)
 {
 	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
-
-	if ((line6pcm->flags & MASK_CAPTURE) == 0) {
-		line6_unlink_wait_clear_audio_in_urbs(line6pcm);
-		line6_free_capture_buffer(line6pcm);
-	}
-
+	line6_pcm_release(line6pcm, LINE6_BIT_PCM_ALSA_CAPTURE_BUFFER);
 	return snd_pcm_lib_free_pages(substream);
 }
 
@@ -380,7 +356,7 @@ int snd_line6_capture_trigger(struct snd_line6_pcm *line6pcm, int cmd)
 #ifdef CONFIG_PM
 	case SNDRV_PCM_TRIGGER_RESUME:
 #endif
-		err = line6_pcm_start(line6pcm, MASK_PCM_ALSA_CAPTURE);
+		err = line6_pcm_acquire(line6pcm, LINE6_BIT_PCM_ALSA_CAPTURE_STREAM);
 
 		if (err < 0)
 			return err;
@@ -391,7 +367,7 @@ int snd_line6_capture_trigger(struct snd_line6_pcm *line6pcm, int cmd)
 #ifdef CONFIG_PM
 	case SNDRV_PCM_TRIGGER_SUSPEND:
 #endif
-		err = line6_pcm_stop(line6pcm, MASK_PCM_ALSA_CAPTURE);
+		err = line6_pcm_release(line6pcm, LINE6_BIT_PCM_ALSA_CAPTURE_STREAM);
 
 		if (err < 0)
 			return err;
diff --git a/drivers/staging/line6/capture.h b/drivers/staging/line6/capture.h
index 366cbaa7c88..4157bcb598a 100644
--- a/drivers/staging/line6/capture.h
+++ b/drivers/staging/line6/capture.h
@@ -19,7 +19,6 @@
 
 extern struct snd_pcm_ops snd_line6_capture_ops;
 
-extern int line6_alloc_capture_buffer(struct snd_line6_pcm *line6pcm);
 extern void line6_capture_copy(struct snd_line6_pcm *line6pcm, char *fbuf,
 			       int fsize);
 extern void line6_capture_check_period(struct snd_line6_pcm *line6pcm,
@@ -30,6 +29,7 @@ extern int line6_submit_audio_in_all_urbs(struct snd_line6_pcm *line6pcm);
 extern void line6_unlink_audio_in_urbs(struct snd_line6_pcm *line6pcm);
 extern void line6_unlink_wait_clear_audio_in_urbs(struct snd_line6_pcm
 						  *line6pcm);
+extern void line6_wait_clear_audio_in_urbs(struct snd_line6_pcm *line6pcm);
 extern int snd_line6_capture_trigger(struct snd_line6_pcm *line6pcm, int cmd);
 
 #endif
diff --git a/drivers/staging/line6/driver.c b/drivers/staging/line6/driver.c
index 6a1959e16e0..e8023afd365 100644
--- a/drivers/staging/line6/driver.c
+++ b/drivers/staging/line6/driver.c
@@ -1346,7 +1346,7 @@ static void __exit line6_exit(void)
 		if (line6pcm == NULL)
 			continue;
 
-		line6_pcm_stop(line6pcm, ~0);
+		line6_pcm_release(line6pcm, ~0);
 	}
 
 	usb_deregister(&line6_driver);
diff --git a/drivers/staging/line6/pcm.c b/drivers/staging/line6/pcm.c
index 37675e66da8..90d2d4475cb 100644
--- a/drivers/staging/line6/pcm.c
+++ b/drivers/staging/line6/pcm.c
@@ -52,9 +52,9 @@ static ssize_t pcm_set_impulse_volume(struct device *dev,
 	line6pcm->impulse_volume = value;
 
 	if (value > 0)
-		line6_pcm_start(line6pcm, MASK_PCM_IMPULSE);
+		line6_pcm_acquire(line6pcm, LINE6_BITS_PCM_IMPULSE);
 	else
-		line6_pcm_stop(line6pcm, MASK_PCM_IMPULSE);
+		line6_pcm_release(line6pcm, LINE6_BITS_PCM_IMPULSE);
 
 	return count;
 }
@@ -92,29 +92,43 @@ static bool test_flags(unsigned long flags0, unsigned long flags1,
 	return ((flags0 & mask) == 0) && ((flags1 & mask) != 0);
 }
 
-int line6_pcm_start(struct snd_line6_pcm *line6pcm, int channels)
+int line6_pcm_acquire(struct snd_line6_pcm *line6pcm, int channels)
 {
 	unsigned long flags_old =
 	    __sync_fetch_and_or(&line6pcm->flags, channels);
 	unsigned long flags_new = flags_old | channels;
+	unsigned long flags_final = flags_old;
 	int err = 0;
 	
 	line6pcm->prev_fbuf = NULL;
 
-	if (test_flags(flags_old, flags_new, MASK_CAPTURE)) {
+	if (test_flags(flags_old, flags_new, LINE6_BITS_CAPTURE_BUFFER)) {
+		/* We may be invoked multiple times in a row so allocate once only */
+		if (!line6pcm->buffer_in) {
+			line6pcm->buffer_in =
+				kmalloc(LINE6_ISO_BUFFERS * LINE6_ISO_PACKETS *
+					line6pcm->max_packet_size, GFP_KERNEL);
+
+			if (!line6pcm->buffer_in) {
+				dev_err(line6pcm->line6->ifcdev,
+					"cannot malloc capture buffer\n");
+				err = -ENOMEM;
+				goto pcm_acquire_error;
+			}
+
+			flags_final |= channels & LINE6_BITS_CAPTURE_BUFFER;
+		}
+	}
+
+	if (test_flags(flags_old, flags_new, LINE6_BITS_CAPTURE_STREAM)) {
 		/*
 		   Waiting for completion of active URBs in the stop handler is
 		   a bug, we therefore report an error if capturing is restarted
 		   too soon.
 		 */
-		if (line6pcm->active_urb_in | line6pcm->unlink_urb_in)
+		if (line6pcm->active_urb_in | line6pcm->unlink_urb_in) {
+			dev_err(line6pcm->line6->ifcdev, "Device not yet ready\n");
 			return -EBUSY;
-
-		if (!(flags_new & MASK_PCM_ALSA_CAPTURE)) {
-			err = line6_alloc_capture_buffer(line6pcm);
-
-			if (err < 0)
-				goto pcm_start_error;
 		}
 
 		line6pcm->count_in = 0;
@@ -122,55 +136,78 @@ int line6_pcm_start(struct snd_line6_pcm *line6pcm, int channels)
 		err = line6_submit_audio_in_all_urbs(line6pcm);
 
 		if (err < 0)
-			goto pcm_start_error;
+			goto pcm_acquire_error;
+
+		flags_final |= channels & LINE6_BITS_CAPTURE_STREAM;
 	}
 
-	if (test_flags(flags_old, flags_new, MASK_PLAYBACK)) {
+	if (test_flags(flags_old, flags_new, LINE6_BITS_PLAYBACK_BUFFER)) {
+		/* We may be invoked multiple times in a row so allocate once only */
+		if (!line6pcm->buffer_out) {
+			line6pcm->buffer_out =
+				kmalloc(LINE6_ISO_BUFFERS * LINE6_ISO_PACKETS *
+					line6pcm->max_packet_size, GFP_KERNEL);
+
+			if (!line6pcm->buffer_out) {
+				dev_err(line6pcm->line6->ifcdev,
+					"cannot malloc playback buffer\n");
+				err = -ENOMEM;
+				goto pcm_acquire_error;
+			}
+
+			flags_final |= channels & LINE6_BITS_PLAYBACK_BUFFER;
+		}
+	}
+
+	if (test_flags(flags_old, flags_new, LINE6_BITS_PLAYBACK_STREAM)) {
 		/*
-		   See comment above regarding PCM restart.
-		 */
-		if (line6pcm->active_urb_out | line6pcm->unlink_urb_out)
+		  See comment above regarding PCM restart.
+		*/
+		if (line6pcm->active_urb_out | line6pcm->unlink_urb_out) {
+			dev_err(line6pcm->line6->ifcdev, "Device not yet ready\n");
 			return -EBUSY;
-
-		if (!(flags_new & MASK_PCM_ALSA_PLAYBACK)) {
-			err = line6_alloc_playback_buffer(line6pcm);
-
-			if (err < 0)
-				goto pcm_start_error;
 		}
 
 		line6pcm->count_out = 0;
 		err = line6_submit_audio_out_all_urbs(line6pcm);
 
 		if (err < 0)
-			goto pcm_start_error;
+			goto pcm_acquire_error;
+
+		flags_final |= channels & LINE6_BITS_PLAYBACK_STREAM;
 	}
 
 	return 0;
 
-pcm_start_error:
-	__sync_fetch_and_and(&line6pcm->flags, ~channels);
+pcm_acquire_error:
+	/*
+	   If not all requested resources/streams could be obtained, release
+	   those which were successfully obtained (if any).
+	*/
+	line6_pcm_release(line6pcm, flags_final & channels);
 	return err;
 }
 
-int line6_pcm_stop(struct snd_line6_pcm *line6pcm, int channels)
+int line6_pcm_release(struct snd_line6_pcm *line6pcm, int channels)
 {
 	unsigned long flags_old =
 	    __sync_fetch_and_and(&line6pcm->flags, ~channels);
 	unsigned long flags_new = flags_old & ~channels;
 
-	if (test_flags(flags_new, flags_old, MASK_CAPTURE)) {
+	if (test_flags(flags_new, flags_old, LINE6_BITS_CAPTURE_STREAM))
 		line6_unlink_audio_in_urbs(line6pcm);
 
-		if (!(flags_old & MASK_PCM_ALSA_CAPTURE))
-			line6_free_capture_buffer(line6pcm);
+	if (test_flags(flags_new, flags_old, LINE6_BITS_CAPTURE_BUFFER)) {
+		line6_wait_clear_audio_in_urbs(line6pcm);
+		line6_free_capture_buffer(line6pcm);
 	}
 
-	if (test_flags(flags_new, flags_old, MASK_PLAYBACK)) {
+	if (test_flags(flags_new, flags_old, LINE6_BITS_PLAYBACK_STREAM))
 		line6_unlink_audio_out_urbs(line6pcm);
 
-		if (!(flags_old & MASK_PCM_ALSA_PLAYBACK))
-			line6_free_playback_buffer(line6pcm);
+	if (test_flags(flags_new, flags_old, LINE6_BITS_PLAYBACK_BUFFER)) {
+		line6_wait_clear_audio_out_urbs(line6pcm);
+		line6_free_playback_buffer(line6pcm);
 	}
 
 	return 0;
@@ -185,7 +222,7 @@ int snd_line6_trigger(struct snd_pcm_substream *substream, int cmd)
 	unsigned long flags;
 
 	spin_lock_irqsave(&line6pcm->lock_trigger, flags);
-	clear_bit(BIT_PREPARED, &line6pcm->flags);
+	clear_bit(LINE6_INDEX_PREPARED, &line6pcm->flags);
 
 	snd_pcm_group_for_each_entry(s, substream) {
 		switch (s->stream) {
@@ -498,13 +535,13 @@ int snd_line6_prepare(struct snd_pcm_substream *substream)
 
 	switch (substream->stream) {
 	case SNDRV_PCM_STREAM_PLAYBACK:
-		if ((line6pcm->flags & MASK_PLAYBACK) == 0)
+		if ((line6pcm->flags & LINE6_BITS_PLAYBACK_STREAM) == 0)
 			line6_unlink_wait_clear_audio_out_urbs(line6pcm);
 
 		break;
 
 	case SNDRV_PCM_STREAM_CAPTURE:
-		if ((line6pcm->flags & MASK_CAPTURE) == 0)
+		if ((line6pcm->flags & LINE6_BITS_CAPTURE_STREAM) == 0)
 			line6_unlink_wait_clear_audio_in_urbs(line6pcm);
 
 		break;
@@ -513,7 +550,7 @@ int snd_line6_prepare(struct snd_pcm_substream *substream)
 		MISSING_CASE;
 	}
 
-	if (!test_and_set_bit(BIT_PREPARED, &line6pcm->flags)) {
+	if (!test_and_set_bit(LINE6_INDEX_PREPARED, &line6pcm->flags)) {
 		line6pcm->count_out = 0;
 		line6pcm->pos_out = 0;
 		line6pcm->pos_out_done = 0;
diff --git a/drivers/staging/line6/pcm.h b/drivers/staging/line6/pcm.h
index 47c6d6942b4..5210ec8dbe1 100644
--- a/drivers/staging/line6/pcm.h
+++ b/drivers/staging/line6/pcm.h
@@ -46,57 +46,131 @@
 		(line6pcm->pcm->streams[stream].substream)
 
 /*
-	PCM mode bits and masks.
-	"ALSA": operations triggered by applications via ALSA
-	"MONITOR": software monitoring
-	"IMPULSE": optional impulse response operation
+	PCM mode bits.
+
+	There are several features of the Line6 USB driver which require PCM
+	data to be exchanged with the device:
+	*) PCM playback and capture via ALSA
+	*) software monitoring (for devices without hardware monitoring)
+	*) optional impulse response measurement
+	However, from the device's point of view, there is just a single
+	capture and playback stream, which must be shared between these
+	subsystems. It is therefore necessary to maintain the state of the
+	subsystems with respect to PCM usage. We define several constants of
+	the form LINE6_BIT_PCM_<subsystem>_<direction>_<resource> with the
+	following meanings:
+	*) <subsystem> is one of
+	-) ALSA: PCM playback and capture via ALSA
+	-) MONITOR: software monitoring
+	-) IMPULSE: optional impulse response measurement
+	*) <direction> is one of
+	-) PLAYBACK: audio output (from host to device)
+	-) CAPTURE: audio input (from device to host)
+	*) <resource> is one of
+	-) BUFFER: buffer required by PCM data stream
+	-) STREAM: actual PCM data stream
+
+	The subsystems call line6_pcm_acquire() to acquire the (shared)
+	resources needed for a particular operation (e.g., allocate the buffer
+	for ALSA playback or start the capture stream for software monitoring).
+	When a resource is no longer needed, it is released by calling
+	line6_pcm_release(). Buffer allocation and stream startup are handled
+	separately to allow the ALSA kernel driver to perform them at
+	appropriate places (since the callback which starts a PCM stream is not
+	allowed to sleep).
 */
 enum {
-	/* individual bits: */
-	BIT_PCM_ALSA_PLAYBACK,
-	BIT_PCM_ALSA_CAPTURE,
-	BIT_PCM_MONITOR_PLAYBACK,
-	BIT_PCM_MONITOR_CAPTURE,
+	/* individual bit indices: */
+	LINE6_INDEX_PCM_ALSA_PLAYBACK_BUFFER,
+	LINE6_INDEX_PCM_ALSA_PLAYBACK_STREAM,
+	LINE6_INDEX_PCM_ALSA_CAPTURE_BUFFER,
+	LINE6_INDEX_PCM_ALSA_CAPTURE_STREAM,
+	LINE6_INDEX_PCM_MONITOR_PLAYBACK_BUFFER,
+	LINE6_INDEX_PCM_MONITOR_PLAYBACK_STREAM,
+	LINE6_INDEX_PCM_MONITOR_CAPTURE_BUFFER,
+	LINE6_INDEX_PCM_MONITOR_CAPTURE_STREAM,
 #ifdef CONFIG_LINE6_USB_IMPULSE_RESPONSE
-	BIT_PCM_IMPULSE_PLAYBACK,
-	BIT_PCM_IMPULSE_CAPTURE,
+	LINE6_INDEX_PCM_IMPULSE_PLAYBACK_BUFFER,
+	LINE6_INDEX_PCM_IMPULSE_PLAYBACK_STREAM,
+	LINE6_INDEX_PCM_IMPULSE_CAPTURE_BUFFER,
+	LINE6_INDEX_PCM_IMPULSE_CAPTURE_STREAM,
 #endif
-	BIT_PAUSE_PLAYBACK,
-	BIT_PREPARED,
+	LINE6_INDEX_PAUSE_PLAYBACK,
+	LINE6_INDEX_PREPARED,
 
-	/* individual masks: */
-/* *INDENT-OFF* */
-	MASK_PCM_ALSA_PLAYBACK    = 1 << BIT_PCM_ALSA_PLAYBACK,
-	MASK_PCM_ALSA_CAPTURE     = 1 << BIT_PCM_ALSA_CAPTURE,
-	MASK_PCM_MONITOR_PLAYBACK = 1 << BIT_PCM_MONITOR_PLAYBACK,
-	MASK_PCM_MONITOR_CAPTURE  = 1 << BIT_PCM_MONITOR_CAPTURE,
+	/* individual bit masks: */
+	LINE6_BIT(PCM_ALSA_PLAYBACK_BUFFER),
+	LINE6_BIT(PCM_ALSA_PLAYBACK_STREAM),
+	LINE6_BIT(PCM_ALSA_CAPTURE_BUFFER),
+	LINE6_BIT(PCM_ALSA_CAPTURE_STREAM),
+	LINE6_BIT(PCM_MONITOR_PLAYBACK_BUFFER),
+	LINE6_BIT(PCM_MONITOR_PLAYBACK_STREAM),
+	LINE6_BIT(PCM_MONITOR_CAPTURE_BUFFER),
+	LINE6_BIT(PCM_MONITOR_CAPTURE_STREAM),
 #ifdef CONFIG_LINE6_USB_IMPULSE_RESPONSE
-	MASK_PCM_IMPULSE_PLAYBACK = 1 << BIT_PCM_IMPULSE_PLAYBACK,
-	MASK_PCM_IMPULSE_CAPTURE  = 1 << BIT_PCM_IMPULSE_CAPTURE,
+	LINE6_BIT(PCM_IMPULSE_PLAYBACK_BUFFER),
+	LINE6_BIT(PCM_IMPULSE_PLAYBACK_STREAM),
+	LINE6_BIT(PCM_IMPULSE_CAPTURE_BUFFER),
+	LINE6_BIT(PCM_IMPULSE_CAPTURE_STREAM),
 #endif
-	MASK_PAUSE_PLAYBACK       = 1 << BIT_PAUSE_PLAYBACK,
-	MASK_PREPARED             = 1 << BIT_PREPARED,
-/* *INDENT-ON* */
+	LINE6_BIT(PAUSE_PLAYBACK),
+	LINE6_BIT(PREPARED),
+
+	/* combined bit masks (by operation): */
+	LINE6_BITS_PCM_ALSA_BUFFER =
+	    LINE6_BIT_PCM_ALSA_PLAYBACK_BUFFER |
+	    LINE6_BIT_PCM_ALSA_CAPTURE_BUFFER,
+
+	LINE6_BITS_PCM_ALSA_STREAM =
+	    LINE6_BIT_PCM_ALSA_PLAYBACK_STREAM |
+	    LINE6_BIT_PCM_ALSA_CAPTURE_STREAM,
+
+	LINE6_BITS_PCM_MONITOR =
+	    LINE6_BIT_PCM_MONITOR_PLAYBACK_BUFFER |
+	    LINE6_BIT_PCM_MONITOR_PLAYBACK_STREAM |
+	    LINE6_BIT_PCM_MONITOR_CAPTURE_BUFFER |
+	    LINE6_BIT_PCM_MONITOR_CAPTURE_STREAM,
 
-	/* combined masks (by operation): */
-	MASK_PCM_ALSA = MASK_PCM_ALSA_PLAYBACK | MASK_PCM_ALSA_CAPTURE,
-	MASK_PCM_MONITOR = MASK_PCM_MONITOR_PLAYBACK | MASK_PCM_MONITOR_CAPTURE,
 #ifdef CONFIG_LINE6_USB_IMPULSE_RESPONSE
-	MASK_PCM_IMPULSE = MASK_PCM_IMPULSE_PLAYBACK | MASK_PCM_IMPULSE_CAPTURE,
+	LINE6_BITS_PCM_IMPULSE =
+	    LINE6_BIT_PCM_IMPULSE_PLAYBACK_BUFFER |
+	    LINE6_BIT_PCM_IMPULSE_PLAYBACK_STREAM |
+	    LINE6_BIT_PCM_IMPULSE_CAPTURE_BUFFER |
+	    LINE6_BIT_PCM_IMPULSE_CAPTURE_STREAM,
 #endif
 
-	/* combined masks (by direction): */
+	/* combined bit masks (by direction): */
+	LINE6_BITS_PLAYBACK_BUFFER =
 #ifdef CONFIG_LINE6_USB_IMPULSE_RESPONSE
-	MASK_PLAYBACK =
-	    MASK_PCM_ALSA_PLAYBACK | MASK_PCM_MONITOR_PLAYBACK |
-	    MASK_PCM_IMPULSE_PLAYBACK,
-	MASK_CAPTURE =
-	    MASK_PCM_ALSA_CAPTURE | MASK_PCM_MONITOR_CAPTURE |
-	    MASK_PCM_IMPULSE_CAPTURE
-#else
-	MASK_PLAYBACK = MASK_PCM_ALSA_PLAYBACK | MASK_PCM_MONITOR_PLAYBACK,
-	MASK_CAPTURE = MASK_PCM_ALSA_CAPTURE | MASK_PCM_MONITOR_CAPTURE
+	    LINE6_BIT_PCM_IMPULSE_PLAYBACK_BUFFER |
 #endif
+	    LINE6_BIT_PCM_ALSA_PLAYBACK_BUFFER |
+	    LINE6_BIT_PCM_MONITOR_PLAYBACK_BUFFER ,
+
+	LINE6_BITS_PLAYBACK_STREAM =
+#ifdef CONFIG_LINE6_USB_IMPULSE_RESPONSE
+	    LINE6_BIT_PCM_IMPULSE_PLAYBACK_STREAM |
+#endif
+	    LINE6_BIT_PCM_ALSA_PLAYBACK_STREAM |
+	    LINE6_BIT_PCM_MONITOR_PLAYBACK_STREAM ,
+
+	LINE6_BITS_CAPTURE_BUFFER =
+#ifdef CONFIG_LINE6_USB_IMPULSE_RESPONSE
+	    LINE6_BIT_PCM_IMPULSE_CAPTURE_BUFFER |
+#endif
+	    LINE6_BIT_PCM_ALSA_CAPTURE_BUFFER |
+	    LINE6_BIT_PCM_MONITOR_CAPTURE_BUFFER ,
+
+	LINE6_BITS_CAPTURE_STREAM =
+#ifdef CONFIG_LINE6_USB_IMPULSE_RESPONSE
+	    LINE6_BIT_PCM_IMPULSE_CAPTURE_STREAM |
+#endif
+	    LINE6_BIT_PCM_ALSA_CAPTURE_STREAM |
+	    LINE6_BIT_PCM_MONITOR_CAPTURE_STREAM,
+	
+	LINE6_BITS_STREAM =
+	    LINE6_BITS_PLAYBACK_STREAM |
+	    LINE6_BITS_CAPTURE_STREAM
 };
 
 struct line6_pcm_properties {
@@ -290,7 +364,7 @@ struct snd_line6_pcm {
 #endif
 
 	/**
-		 Several status bits (see BIT_*).
+		 Several status bits (see LINE6_BIT_*).
 	*/
 	unsigned long flags;
 
@@ -302,7 +376,7 @@ extern int line6_init_pcm(struct usb_line6 *line6,
 extern int snd_line6_trigger(struct snd_pcm_substream *substream, int cmd);
 extern int snd_line6_prepare(struct snd_pcm_substream *substream);
 extern void line6_pcm_disconnect(struct snd_line6_pcm *line6pcm);
-extern int line6_pcm_start(struct snd_line6_pcm *line6pcm, int channels);
-extern int line6_pcm_stop(struct snd_line6_pcm *line6pcm, int channels);
+extern int line6_pcm_acquire(struct snd_line6_pcm *line6pcm, int channels);
+extern int line6_pcm_release(struct snd_line6_pcm *line6pcm, int channels);
 
 #endif
diff --git a/drivers/staging/line6/playback.c b/drivers/staging/line6/playback.c
index 4152db2328b..a0ab9d0493f 100644
--- a/drivers/staging/line6/playback.c
+++ b/drivers/staging/line6/playback.c
@@ -166,7 +166,7 @@ static int submit_audio_out_urb(struct snd_line6_pcm *line6pcm)
 		struct usb_iso_packet_descriptor *fout =
 		    &urb_out->iso_frame_desc[i];
 
-		if (line6pcm->flags & MASK_CAPTURE)
+		if (line6pcm->flags & LINE6_BITS_CAPTURE_STREAM)
 			fsize = line6pcm->prev_fsize;
 
 		if (fsize == 0) {
@@ -196,8 +196,8 @@ static int submit_audio_out_urb(struct snd_line6_pcm *line6pcm)
 	urb_out->transfer_buffer_length = urb_size;
 	urb_out->context = line6pcm;
 
-	if (test_bit(BIT_PCM_ALSA_PLAYBACK, &line6pcm->flags) &&
-	    !test_bit(BIT_PAUSE_PLAYBACK, &line6pcm->flags)) {
+	if (test_bit(LINE6_INDEX_PCM_ALSA_PLAYBACK_STREAM, &line6pcm->flags) &&
+	    !test_bit(LINE6_INDEX_PAUSE_PLAYBACK, &line6pcm->flags)) {
 		struct snd_pcm_runtime *runtime =
 		    get_substream(line6pcm, SNDRV_PCM_STREAM_PLAYBACK)->runtime;
 
@@ -238,10 +238,10 @@ static int submit_audio_out_urb(struct snd_line6_pcm *line6pcm)
 
 	if (line6pcm->prev_fbuf != NULL) {
 #ifdef CONFIG_LINE6_USB_IMPULSE_RESPONSE
-		if (line6pcm->flags & MASK_PCM_IMPULSE) {
+		if (line6pcm->flags & LINE6_BITS_PCM_IMPULSE) {
 			create_impulse_test_signal(line6pcm, urb_out,
 						   bytes_per_frame);
-			if (line6pcm->flags & MASK_PCM_ALSA_CAPTURE) {
+			if (line6pcm->flags & LINE6_BIT_PCM_ALSA_CAPTURE_STREAM) {
 				line6_capture_copy(line6pcm,
 						   urb_out->transfer_buffer,
 						   urb_out->
@@ -254,8 +254,8 @@ static int submit_audio_out_urb(struct snd_line6_pcm *line6pcm)
 			if (!
 			    (line6pcm->line6->
 			     properties->capabilities & LINE6_BIT_HWMON)
-&& (line6pcm->flags & MASK_PLAYBACK)
-&& (line6pcm->flags & MASK_CAPTURE))
+			    && (line6pcm->flags & LINE6_BITS_PLAYBACK_STREAM)
+			    && (line6pcm->flags & LINE6_BITS_CAPTURE_STREAM))
 				add_monitor_signal(urb_out, line6pcm->prev_fbuf,
 						   line6pcm->volume_monitor,
 						   bytes_per_frame);
@@ -321,7 +321,7 @@ void line6_unlink_audio_out_urbs(struct snd_line6_pcm *line6pcm)
 /*
 	Wait until unlinking of all currently active playback URBs has been finished.
 */
-static void wait_clear_audio_out_urbs(struct snd_line6_pcm *line6pcm)
+void line6_wait_clear_audio_out_urbs(struct snd_line6_pcm *line6pcm)
 {
 	int timeout = HZ;
 	unsigned int i;
@@ -348,26 +348,7 @@ static void wait_clear_audio_out_urbs(struct snd_line6_pcm *line6pcm)
 void line6_unlink_wait_clear_audio_out_urbs(struct snd_line6_pcm *line6pcm)
 {
 	line6_unlink_audio_out_urbs(line6pcm);
-	wait_clear_audio_out_urbs(line6pcm);
-}
-
-int line6_alloc_playback_buffer(struct snd_line6_pcm *line6pcm)
-{
-	/* We may be invoked multiple times in a row so allocate once only */
-	if (line6pcm->buffer_out)
-		return 0;
-
-	line6pcm->buffer_out =
-		kmalloc(LINE6_ISO_BUFFERS * LINE6_ISO_PACKETS *
-			line6pcm->max_packet_size, GFP_KERNEL);
-
-	if (!line6pcm->buffer_out) {
-		dev_err(line6pcm->line6->ifcdev,
-			"cannot malloc playback buffer\n");
-		return -ENOMEM;
-	}
-
-	return 0;
+	line6_wait_clear_audio_out_urbs(line6pcm);
 }
 
 void line6_free_playback_buffer(struct snd_line6_pcm *line6pcm)
@@ -407,7 +388,7 @@ static void audio_out_callback(struct urb *urb)
 
 	spin_lock_irqsave(&line6pcm->lock_audio_out, flags);
 
-	if (test_bit(BIT_PCM_ALSA_PLAYBACK, &line6pcm->flags)) {
+	if (test_bit(LINE6_INDEX_PCM_ALSA_PLAYBACK_STREAM, &line6pcm->flags)) {
 		struct snd_pcm_runtime *runtime = substream->runtime;
 		line6pcm->pos_out_done +=
 		    length / line6pcm->properties->bytes_per_frame;
@@ -432,7 +413,7 @@ static void audio_out_callback(struct urb *urb)
 	if (!shutdown) {
 		submit_audio_out_urb(line6pcm);
 
-		if (test_bit(BIT_PCM_ALSA_PLAYBACK, &line6pcm->flags)) {
+		if (test_bit(LINE6_INDEX_PCM_ALSA_PLAYBACK_STREAM, &line6pcm->flags)) {
 			line6pcm->bytes_out += length;
 			if (line6pcm->bytes_out >= line6pcm->period_out) {
 				line6pcm->bytes_out %= line6pcm->period_out;
@@ -484,17 +465,17 @@ static int snd_line6_playback_hw_params(struct snd_pcm_substream *substream,
 	}
 	/* -- [FD] end */
 
-	if ((line6pcm->flags & MASK_PLAYBACK) == 0) {
-		ret = line6_alloc_playback_buffer(line6pcm);
+	ret = line6_pcm_acquire(line6pcm, LINE6_BIT_PCM_ALSA_PLAYBACK_BUFFER);
 
-		if (ret < 0)
-			return ret;
-	}
+	if (ret < 0)
+		return ret;
 
 	ret = snd_pcm_lib_malloc_pages(substream,
 				       params_buffer_bytes(hw_params));
-	if (ret < 0)
+	if (ret < 0) {
+		line6_pcm_release(line6pcm, LINE6_BIT_PCM_ALSA_PLAYBACK_BUFFER);
 		return ret;
+	}
 
 	line6pcm->period_out = params_period_bytes(hw_params);
 	return 0;
@@ -504,12 +485,7 @@ static int snd_line6_playback_hw_params(struct snd_pcm_substream *substream,
 static int snd_line6_playback_hw_free(struct snd_pcm_substream *substream)
 {
 	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
-
-	if ((line6pcm->flags & MASK_PLAYBACK) == 0) {
-		line6_unlink_wait_clear_audio_out_urbs(line6pcm);
-		line6_free_playback_buffer(line6pcm);
-	}
-
+	line6_pcm_release(line6pcm, LINE6_BIT_PCM_ALSA_PLAYBACK_BUFFER);
 	return snd_pcm_lib_free_pages(substream);
 }
 
@@ -523,7 +499,7 @@ int snd_line6_playback_trigger(struct snd_line6_pcm *line6pcm, int cmd)
 #ifdef CONFIG_PM
 	case SNDRV_PCM_TRIGGER_RESUME:
 #endif
-		err = line6_pcm_start(line6pcm, MASK_PCM_ALSA_PLAYBACK);
+		err = line6_pcm_acquire(line6pcm, LINE6_BIT_PCM_ALSA_PLAYBACK_STREAM);
 
 		if (err < 0)
 			return err;
@@ -534,7 +510,7 @@ int snd_line6_playback_trigger(struct snd_line6_pcm *line6pcm, int cmd)
 #ifdef CONFIG_PM
 	case SNDRV_PCM_TRIGGER_SUSPEND:
 #endif
-		err = line6_pcm_stop(line6pcm, MASK_PCM_ALSA_PLAYBACK);
+		err = line6_pcm_release(line6pcm, LINE6_BIT_PCM_ALSA_PLAYBACK_STREAM);
 
 		if (err < 0)
 			return err;
@@ -542,11 +518,11 @@ int snd_line6_playback_trigger(struct snd_line6_pcm *line6pcm, int cmd)
 		break;
 
 	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
-		set_bit(BIT_PAUSE_PLAYBACK, &line6pcm->flags);
+		set_bit(LINE6_INDEX_PAUSE_PLAYBACK, &line6pcm->flags);
 		break;
 
 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
-		clear_bit(BIT_PAUSE_PLAYBACK, &line6pcm->flags);
+		clear_bit(LINE6_INDEX_PAUSE_PLAYBACK, &line6pcm->flags);
 		break;
 
 	default:
diff --git a/drivers/staging/line6/playback.h b/drivers/staging/line6/playback.h
index 02487ff2453..743bd6f74c5 100644
--- a/drivers/staging/line6/playback.h
+++ b/drivers/staging/line6/playback.h
@@ -29,13 +29,13 @@
 
 extern struct snd_pcm_ops snd_line6_playback_ops;
 
-extern int line6_alloc_playback_buffer(struct snd_line6_pcm *line6pcm);
 extern int line6_create_audio_out_urbs(struct snd_line6_pcm *line6pcm);
 extern void line6_free_playback_buffer(struct snd_line6_pcm *line6pcm);
 extern int line6_submit_audio_out_all_urbs(struct snd_line6_pcm *line6pcm);
 extern void line6_unlink_audio_out_urbs(struct snd_line6_pcm *line6pcm);
 extern void line6_unlink_wait_clear_audio_out_urbs(struct snd_line6_pcm
 						   *line6pcm);
+extern void line6_wait_clear_audio_out_urbs(struct snd_line6_pcm *line6pcm);
 extern int snd_line6_playback_trigger(struct snd_line6_pcm *line6pcm, int cmd);
 
 #endif
diff --git a/drivers/staging/line6/toneport.c b/drivers/staging/line6/toneport.c
index b776130058c..b754f69a29c 100644
--- a/drivers/staging/line6/toneport.c
+++ b/drivers/staging/line6/toneport.c
@@ -207,9 +207,9 @@ static int snd_toneport_monitor_put(struct snd_kcontrol *kcontrol,
 	line6pcm->volume_monitor = ucontrol->value.integer.value[0];
 
 	if (line6pcm->volume_monitor > 0)
-		line6_pcm_start(line6pcm, MASK_PCM_MONITOR);
+		line6_pcm_acquire(line6pcm, LINE6_BITS_PCM_MONITOR);
 	else
-		line6_pcm_stop(line6pcm, MASK_PCM_MONITOR);
+		line6_pcm_release(line6pcm, LINE6_BITS_PCM_MONITOR);
 
 	return 1;
 }
@@ -264,7 +264,7 @@ static void toneport_start_pcm(unsigned long arg)
 {
 	struct usb_line6_toneport *toneport = (struct usb_line6_toneport *)arg;
 	struct usb_line6 *line6 = &toneport->line6;
-	line6_pcm_start(line6->line6pcm, MASK_PCM_MONITOR);
+	line6_pcm_acquire(line6->line6pcm, LINE6_BITS_PCM_MONITOR);
 }
 
 /* control definition */
@@ -446,7 +446,7 @@ void line6_toneport_disconnect(struct usb_interface *interface)
 		struct snd_line6_pcm *line6pcm = toneport->line6.line6pcm;
 
 		if (line6pcm != NULL) {
-			line6_pcm_stop(line6pcm, MASK_PCM_MONITOR);
+			line6_pcm_release(line6pcm, LINE6_BITS_PCM_MONITOR);
 			line6_pcm_disconnect(line6pcm);
 		}
 	}
diff --git a/drivers/staging/line6/usbdefs.h b/drivers/staging/line6/usbdefs.h
index aff9e5caea4..353d59d77b0 100644
--- a/drivers/staging/line6/usbdefs.h
+++ b/drivers/staging/line6/usbdefs.h
@@ -39,31 +39,29 @@
 #define LINE6_DEVID_TONEPORT_UX2  0x4142
 #define LINE6_DEVID_VARIAX        0x534d
 
-enum {
-	LINE6_ID_BASSPODXT,
-	LINE6_ID_BASSPODXTLIVE,
-	LINE6_ID_BASSPODXTPRO,
-	LINE6_ID_GUITARPORT,
-	LINE6_ID_POCKETPOD,
-	LINE6_ID_PODHD300,
-	LINE6_ID_PODHD500,
-	LINE6_ID_PODSTUDIO_GX,
-	LINE6_ID_PODSTUDIO_UX1,
-	LINE6_ID_PODSTUDIO_UX2,
-	LINE6_ID_PODX3,
-	LINE6_ID_PODX3LIVE,
-	LINE6_ID_PODXT,
-	LINE6_ID_PODXTLIVE,
-	LINE6_ID_PODXTPRO,
-	LINE6_ID_TONEPORT_GX,
-	LINE6_ID_TONEPORT_UX1,
-	LINE6_ID_TONEPORT_UX2,
-	LINE6_ID_VARIAX
-};
-
-#define LINE6_BIT(x) LINE6_BIT_ ## x = 1 << LINE6_ID_ ## x
+#define LINE6_BIT(x) LINE6_BIT_ ## x = 1 << LINE6_INDEX_ ## x
 
 enum {
+	LINE6_INDEX_BASSPODXT,
+	LINE6_INDEX_BASSPODXTLIVE,
+	LINE6_INDEX_BASSPODXTPRO,
+	LINE6_INDEX_GUITARPORT,
+	LINE6_INDEX_POCKETPOD,
+	LINE6_INDEX_PODHD300,
+	LINE6_INDEX_PODHD500,
+	LINE6_INDEX_PODSTUDIO_GX,
+	LINE6_INDEX_PODSTUDIO_UX1,
+	LINE6_INDEX_PODSTUDIO_UX2,
+	LINE6_INDEX_PODX3,
+	LINE6_INDEX_PODX3LIVE,
+	LINE6_INDEX_PODXT,
+	LINE6_INDEX_PODXTLIVE,
+	LINE6_INDEX_PODXTPRO,
+	LINE6_INDEX_TONEPORT_GX,
+	LINE6_INDEX_TONEPORT_UX1,
+	LINE6_INDEX_TONEPORT_UX2,
+	LINE6_INDEX_VARIAX,
+
 	LINE6_BIT(BASSPODXT),
 	LINE6_BIT(BASSPODXTLIVE),
 	LINE6_BIT(BASSPODXTPRO),