staging: line6: separate handling of buffer allocation and stream startup

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).

Signed-off-by: Markus Grabner <grabner@icg.tugraz.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

9 files changed, 254 insertions, 193 deletions

diff --git a/drivers/staging/line6/capture.c b/drivers/staging/line6/capture.c
index 127f95247749..c85c5b6bffb7 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 366cbaa7c88d..4157bcb598a9 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 6a1959e16e00..e8023afd3656 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 37675e66da81..90d2d4475cb4 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)) {
-		/*
-		   See comment above regarding PCM restart.
-		 */
-		if (line6pcm->active_urb_out | line6pcm->unlink_urb_out)
-			return -EBUSY;
+	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;
+			}
 
-		if (!(flags_new & MASK_PCM_ALSA_PLAYBACK)) {
-			err = line6_alloc_playback_buffer(line6pcm);
+			flags_final |= channels & LINE6_BITS_PLAYBACK_BUFFER;
+		}
+	}
 
-			if (err < 0)
-				goto pcm_start_error;
+	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) {
+			dev_err(line6pcm->line6->ifcdev, "Device not yet ready\n");
+			return -EBUSY;
 		}
 
 		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 47c6d6942b4f..5210ec8dbe16 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,
-
-	/* 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,
+	LINE6_INDEX_PAUSE_PLAYBACK,
+	LINE6_INDEX_PREPARED,
+
+	/* 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 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,
+	/* 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,
+
+#ifdef CONFIG_LINE6_USB_IMPULSE_RESPONSE
+	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 bit masks (by direction): */
+	LINE6_BITS_PLAYBACK_BUFFER =
+#ifdef CONFIG_LINE6_USB_IMPULSE_RESPONSE
+	    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
-	MASK_PCM_IMPULSE = MASK_PCM_IMPULSE_PLAYBACK | MASK_PCM_IMPULSE_CAPTURE,
+	    LINE6_BIT_PCM_IMPULSE_CAPTURE_BUFFER |
 #endif
+	    LINE6_BIT_PCM_ALSA_CAPTURE_BUFFER |
+	    LINE6_BIT_PCM_MONITOR_CAPTURE_BUFFER ,
 
-	/* combined masks (by direction): */
+	LINE6_BITS_CAPTURE_STREAM =
 #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_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 4152db2328b7..a0ab9d0493fa 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 02487ff24538..743bd6f74c57 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 b776130058ca..b754f69a29c4 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 aff9e5caea46..353d59d77b04 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),