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>

1 files changed, 22 insertions, 46 deletions

diff --git a/drivers/staging/line6/playback.c b/drivers/staging/line6/playback.c
index 4152db2..a0ab9d0 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: