[PATCH] make snd-aloop loopback device work

[PATCH] make snd-aloop loopback device work

[Ahmet İnan]

[-- Attachment #1: Type: text/plain, Size: 1819 bytes --]

ive merged the previously mentioned 2 working implementations into one file
and made them switchable thru preprocessor directives.
the secure one is the default.

its now fullduplex, this means:

aplay -D hw:0,0 lala.wav
ecasound -i:alsahw,0,1,0

works exactly the same like:

aplay -D hw:0,1 lala.wav
ecasound -i:alsahw,0,0,0

it would be nice if it could be included in the tree, so that other ppl can
test this and yell at me when something is wrong.

still need to workout this pcm_jiffies problem, but when its done then i will
also provide an patch for dummy.c, couse it suffers the same problem on
HZ > 100 kernels.

================================================================
Summary: make snd-aloop loopback device work

the snd-aloop device is a full-duplex loopback device, that can
be used to connect 2 apps together, so that each apps output
gets the input of the other app.

the first app forces the second app to use its settings, so
no rate, format or channel number conversion is done.

examples (hw:0 is loopback, !default is real soundcard / dmix):

capture output from other apps to hdd:
aplay -D hw:0,0 play.wav
arecord -D hw:0,1 record.wav

the same:
aplay -D hw:0,1 play.wav
arecord -D hw:0,0 record.wav

or have more fun:
ecasound -f:16,2,48000 -i:alsahw,0,1,0 &
ecasound -f:16,2,48000 -i:alsahw,0,1,1 &
ecasound -f:16,2,48000 -i:alsahw,0,1,2 &
...
now open up to 8 oss apps _without_ aoss, sit back and relax.

Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>
================================================================

files:
http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-driver-1.0.13-aloop-ainan-patch.diff
http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/aloop-kernel.c

ahmet


[-- Attachment #2: alsa-driver-1.0.13-aloop-ainan-patch.diff --]
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--- alsa-driver-1.0.13.orig/drivers/aloop-kernel.c	2006-09-29 13:40:29.000000000 +0200
+++ alsa-driver-1.0.13/drivers/aloop-kernel.c	2006-12-20 21:54:55.438121716 +0100
@@ -30,19 +30,24 @@
 #include <sound/pcm.h>
 #include <sound/initval.h>
 
+/* comment out for experimental non-memcpy code */
+#define SND_CARD_LOOPBACK_COPY_RINGBUFFER
+/* comment in to trash your kernel logfiles */
+/* #define SND_CARD_LOOPBACK_VERBOSE */
+
 MODULE_AUTHOR("Jaroslav Kysela <perex@suse.cz>");
 MODULE_DESCRIPTION("A loopback soundcard");
 MODULE_LICENSE("GPL");
 MODULE_SUPPORTED_DEVICE("{{ALSA,Loopback soundcard}}");
 
-#define MAX_PCM_SUBSTREAMS	256
+#define MAX_PCM_SUBSTREAMS	8
 
 static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;	/* Index 0-MAX */
 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;	/* ID for this card */
 static int enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
 static int pcm_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 1};
 static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
-//static int midi_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 2};
+/* static int midi_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 2}; */
 
 module_param_array(index, int, NULL, 0444);
 MODULE_PARM_DESC(index, "Index value for loopback soundcard.");
@@ -53,12 +58,26 @@
 module_param_array(pcm_devs, int, NULL, 0444);
 MODULE_PARM_DESC(pcm_devs, "PCM devices # (0-4) for loopback driver.");
 module_param_array(pcm_substreams, int, NULL, 0444);
-MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-16) for loopback driver.");
-//module_param_array(midi_devs, int, NULL, 0444);
-//MODULE_PARM_DESC(midi_devs, "MIDI devices # (0-2) for loopback driver.");
+MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-8) for loopback driver.");
+/* module_param_array(midi_devs, int, NULL, 0444);
+ * MODULE_PARM_DESC(midi_devs, "MIDI devices # (0-2) for loopback driver."); */
+
+typedef struct snd_card_loopback_cable {
+	struct snd_pcm_substream *playback;
+	struct snd_pcm_substream *capture;
+	struct snd_pcm_hardware hw;
+	int playback_valid;
+	int capture_valid;
+	int playback_running;
+	int capture_running;
+	int playback_busy;
+	int capture_busy;
+	unsigned int pcm_buf_pos;
+} snd_card_loopback_cable_t;
 
 typedef struct snd_card_loopback {
 	struct snd_card *card;
+	struct snd_card_loopback_cable cables[MAX_PCM_SUBSTREAMS][2];
 } snd_card_loopback_t;
 
 typedef struct snd_card_loopback_pcm {
@@ -72,12 +91,57 @@
 	unsigned int pcm_irq_pos;	/* IRQ position */
 	unsigned int pcm_buf_pos;	/* position in buffer */
 	struct snd_pcm_substream *substream;
+	struct snd_card_loopback_cable *cable;
 } snd_card_loopback_pcm_t;
 
 static struct snd_card *snd_loopback_cards[SNDRV_CARDS] = SNDRV_DEFAULT_PTR;
 
+#ifdef SND_CARD_LOOPBACK_COPY_RINGBUFFER
+static void ringbuffer_copy(
+		unsigned char *dst, size_t dst_pos, size_t dst_size,
+		unsigned char *src, size_t src_pos, size_t src_size,
+		size_t bytes)
+{
+	size_t moon, star;
+	size_t dst_pos_bytes, src_pos_bytes;
+
+	dst_pos_bytes = dst_pos + bytes;
+	src_pos_bytes = src_pos + bytes;
+	if (dst_pos_bytes <= dst_size) {
+		if (src_pos_bytes <= src_size) {
+			memcpy(dst + dst_pos, src + src_pos, bytes);
+		} else {
+			moon = src_size - src_pos;
+			memcpy(dst + dst_pos, src + src_pos, moon);
+			memcpy(dst + dst_pos + moon, src, bytes - moon);
+		}
+		return;
+	}
+
+	if (src_pos_bytes <= src_size) {
+		star = dst_size - dst_pos;
+		memcpy(dst + dst_pos, src + src_pos, star);
+		memcpy(dst, src + src_pos + star, bytes - star);
+		return;
+	}
 
-static void snd_card_loopback_pcm_timer_start(struct snd_pcm_substream *substream)
+	moon = dst_size - dst_pos;
+	star = src_size - src_pos;
+	if (moon < star) {
+		star -= moon;
+		memcpy(dst + dst_pos, src + src_pos, moon);
+		memcpy(dst, src + src_pos + moon, star);
+		memcpy(dst + star, src, src_pos_bytes - src_size);
+	} else {
+		moon -= star;
+		memcpy(dst + dst_pos, src + src_pos, star);
+		memcpy(dst + dst_pos + star, src, moon);
+		memcpy(dst, src + moon, dst_pos_bytes - dst_size);
+	}
+}
+#endif /* #ifdef SND_CARD_LOOPBACK_COPY_RINGBUFFER */
+
+static void snd_card_loopback_timer_start(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
@@ -86,7 +150,7 @@
 	add_timer(&dpcm->timer);
 }
 
-static void snd_card_loopback_pcm_timer_stop(struct snd_pcm_substream *substream)
+static void snd_card_loopback_timer_stop(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
@@ -97,10 +161,32 @@
 static int snd_card_loopback_playback_trigger(struct snd_pcm_substream *substream,
 					   int cmd)
 {
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
 	if (cmd == SNDRV_PCM_TRIGGER_START) {
-		snd_card_loopback_pcm_timer_start(substream);
+#ifndef SND_CARD_LOOPBACK_COPY_RINGBUFFER
+		/* put playback pos one period ahead capture pos */
+		dpcm->pcm_buf_pos = (dpcm->cable->pcm_buf_pos +
+			dpcm->pcm_count) % dpcm->pcm_size;
+		dpcm->pcm_irq_pos = 0;
+#endif
+		dpcm->cable->playback_running = 1;
+		snd_card_loopback_timer_start(substream);
 	} else if (cmd == SNDRV_PCM_TRIGGER_STOP) {
-		snd_card_loopback_pcm_timer_stop(substream);
+		dpcm->cable->playback_running = 0;
+		snd_card_loopback_timer_stop(substream);
+#ifndef SND_CARD_LOOPBACK_COPY_RINGBUFFER
+		snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
+				bytes_to_samples(runtime, runtime->dma_bytes));
+#else
+		if (dpcm->cable->capture_valid) {
+		snd_pcm_format_set_silence(dpcm->cable->capture->runtime->format,
+				dpcm->cable->capture->runtime->dma_area,
+				bytes_to_samples(dpcm->cable->capture->runtime,
+					dpcm->cable->capture->runtime->dma_bytes));
+		}
+#endif
+
 	} else {
 		return -EINVAL;
 	}
@@ -110,20 +196,31 @@
 static int snd_card_loopback_capture_trigger(struct snd_pcm_substream *substream,
 					  int cmd)
 {
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
 	if (cmd == SNDRV_PCM_TRIGGER_START) {
-		snd_card_loopback_pcm_timer_start(substream);
+#ifndef SND_CARD_LOOPBACK_COPY_RINGBUFFER
+		/* put capture pos one period behind playback pos */
+		dpcm->pcm_buf_pos = (dpcm->cable->pcm_buf_pos +
+			(dpcm->pcm_size - dpcm->pcm_count)) % dpcm->pcm_size;
+		dpcm->pcm_irq_pos = 0;
+#endif
+		dpcm->cable->capture_running = 1;
+		snd_card_loopback_timer_start(substream);
 	} else if (cmd == SNDRV_PCM_TRIGGER_STOP) {
-		snd_card_loopback_pcm_timer_stop(substream);
+		dpcm->cable->capture_running = 0;
+		snd_card_loopback_timer_stop(substream);
 	} else {
 		return -EINVAL;
 	}
 	return 0;
 }
 
-static int snd_card_loopback_pcm_prepare(struct snd_pcm_substream *substream)
+static int snd_card_loopback_prepare(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
+	snd_card_loopback_cable_t *cable = dpcm->cable;
 	unsigned int bps;
 
 	bps = runtime->rate * runtime->channels;
@@ -133,24 +230,44 @@
 		return -EINVAL;
 	dpcm->pcm_bps = bps;
 	dpcm->pcm_jiffie = bps / HZ;
-	dpcm->pcm_size = snd_pcm_lib_buffer_bytes(substream);
-	dpcm->pcm_count = snd_pcm_lib_period_bytes(substream);
+	dpcm->pcm_size = frames_to_bytes(runtime, runtime->buffer_size);
+	dpcm->pcm_count = frames_to_bytes(runtime, runtime->period_size);
 	dpcm->pcm_irq_pos = 0;
 	dpcm->pcm_buf_pos = 0;
-	return 0;
-}
+	cable->hw.formats = (1ULL << runtime->format);
+	cable->hw.rate_min = runtime->rate;
+	cable->hw.rate_max = runtime->rate;
+	cable->hw.channels_min = runtime->channels;
+	cable->hw.channels_max = runtime->channels;
+#ifndef SND_CARD_LOOPBACK_COPY_RINGBUFFER
+	cable->hw.buffer_bytes_max = frames_to_bytes(runtime, runtime->buffer_size);
+	cable->hw.period_bytes_min = frames_to_bytes(runtime, runtime->period_size);
+	cable->hw.period_bytes_max = frames_to_bytes(runtime, runtime->period_size);
+	cable->hw.periods_min = runtime->periods;
+	cable->hw.periods_max = runtime->periods;
+#endif
 
-static int snd_card_loopback_playback_prepare(struct snd_pcm_substream *substream)
-{
-	return snd_card_loopback_pcm_prepare(substream);
-}
+	snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
+			bytes_to_samples(runtime, runtime->dma_bytes));
 
-static int snd_card_loopback_capture_prepare(struct snd_pcm_substream *substream)
-{
-	return snd_card_loopback_pcm_prepare(substream);
+	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream)
+		cable->playback_valid = 1;
+	else
+		cable->capture_valid = 1;
+
+#ifdef SND_CARD_LOOPBACK_VERBOSE
+	printk(KERN_INFO "snd-aloop(%s): frq=%d chs=%d fmt=%d buf=%d per=%d pers=%d\n",
+			(SNDRV_PCM_STREAM_PLAYBACK == substream->stream ? "playback" : "capture"),
+			runtime->rate, runtime->channels,
+			snd_pcm_format_width(runtime->format),
+			frames_to_bytes(runtime, runtime->buffer_size),
+			frames_to_bytes(runtime, runtime->period_size),
+			runtime->periods);
+#endif
+	return 0;
 }
 
-static void snd_card_loopback_pcm_timer_function(unsigned long data)
+static void snd_card_loopback_timer_function(unsigned long data)
 {
 	snd_card_loopback_pcm_t *dpcm = (snd_card_loopback_pcm_t *)data;
 	
@@ -160,22 +277,51 @@
 	dpcm->pcm_irq_pos += dpcm->pcm_jiffie;
 	dpcm->pcm_buf_pos += dpcm->pcm_jiffie;
 	dpcm->pcm_buf_pos %= dpcm->pcm_size;
+#ifndef SND_CARD_LOOPBACK_COPY_RINGBUFFER
+	dpcm->cable->pcm_buf_pos = dpcm->pcm_buf_pos;
+#endif
 	if (dpcm->pcm_irq_pos >= dpcm->pcm_count) {
 		dpcm->pcm_irq_pos %= dpcm->pcm_count;
+		spin_unlock_irq(&dpcm->lock);	
 		snd_pcm_period_elapsed(dpcm->substream);
+	} else {
+		spin_unlock_irq(&dpcm->lock);
 	}
-	spin_unlock_irq(&dpcm->lock);	
 }
 
-static snd_pcm_uframes_t snd_card_loopback_playback_pointer(struct snd_pcm_substream *substream)
+#ifdef SND_CARD_LOOPBACK_COPY_RINGBUFFER
+static void snd_card_loopback_capture_timer_function(unsigned long data)
 {
-	struct snd_pcm_runtime *runtime = substream->runtime;
-	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
+	snd_card_loopback_pcm_t *playback_dpcm;
+	snd_card_loopback_pcm_t *dpcm = (snd_card_loopback_pcm_t *)data;
+	
+	dpcm->timer.expires = 1 + jiffies;
+	add_timer(&dpcm->timer);
+	spin_lock_irq(&dpcm->lock);
 
-	return bytes_to_frames(runtime, dpcm->pcm_buf_pos);
+	if (dpcm->cable->playback_running) {
+		playback_dpcm = dpcm->cable->playback->runtime->private_data;
+		ringbuffer_copy(dpcm->substream->runtime->dma_area,
+			dpcm->pcm_buf_pos, dpcm->pcm_size,
+			playback_dpcm->substream->runtime->dma_area,
+			playback_dpcm->pcm_buf_pos, playback_dpcm->pcm_size,
+			dpcm->pcm_jiffie);
+	}
+
+	dpcm->pcm_irq_pos += dpcm->pcm_jiffie;
+	dpcm->pcm_buf_pos += dpcm->pcm_jiffie;
+	dpcm->pcm_buf_pos %= dpcm->pcm_size;
+	if (dpcm->pcm_irq_pos >= dpcm->pcm_count) {
+		dpcm->pcm_irq_pos %= dpcm->pcm_count;
+		spin_unlock_irq(&dpcm->lock);	
+		snd_pcm_period_elapsed(dpcm->substream);
+	} else {
+		spin_unlock_irq(&dpcm->lock);	
+	}
 }
+#endif /* #ifdef SND_CARD_LOOPBACK_COPY_RINGBUFFER */
 
-static snd_pcm_uframes_t snd_card_loopback_capture_pointer(struct snd_pcm_substream *substream)
+static snd_pcm_uframes_t snd_card_loopback_pointer(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
@@ -188,16 +334,16 @@
 	.info =			(SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
 				 SNDRV_PCM_INFO_MMAP_VALID),
 	.formats =		(SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S32_LE),
-	.rates =		SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_192000,
-	.rate_min =		5500,
+	.rates =		(SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_192000),
+	.rate_min =		8000,
 	.rate_max =		192000,
 	.channels_min =		1,
 	.channels_max =		32,
-	.buffer_bytes_max =	1024 * 1024,
-	.period_bytes_min =	32,
-	.period_bytes_max =	128 * 1024,
+	.buffer_bytes_max =	64 * 1024,
+	.period_bytes_min =	64,
+	.period_bytes_max =	64 * 1024,
 	.periods_min =		1,
-	.periods_max =		16,
+	.periods_max =		1024,
 	.fifo_size =		0,
 };
 
@@ -210,53 +356,142 @@
 static int snd_card_loopback_hw_params(struct snd_pcm_substream *substream,
 				    struct snd_pcm_hw_params *hw_params)
 {
-	return snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(hw_params));
+#ifndef SND_CARD_LOOPBACK_COPY_RINGBUFFER
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
+#endif
+	if (0 > snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(hw_params)))
+		return -ENOMEM;
+#ifndef SND_CARD_LOOPBACK_COPY_RINGBUFFER
+	/* TODO: no more stealing:
+	 * after letting alsa allocate and configure dma buffers,
+	 * we simply steal the others dma area and overwrite ours. */
+	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream) {
+		if (dpcm->cable->capture_valid)
+			snd_pcm_set_runtime_buffer(substream,
+				dpcm->cable->capture->runtime->dma_buffer_p);
+	} else {
+		if (dpcm->cable->playback_valid)
+			snd_pcm_set_runtime_buffer(substream,
+				dpcm->cable->playback->runtime->dma_buffer_p);
+	}
+#endif
+	return 0;
 }
 
 static int snd_card_loopback_hw_free(struct snd_pcm_substream *substream)
 {
+#ifndef SND_CARD_LOOPBACK_COPY_RINGBUFFER
+	/* TODO: fix this memory leak:
+	 * we stole it and now we cant even bring it back .. damnit. */
+	return 0; /* snd_pcm_lib_free_pages(substream); */
+#else
 	return snd_pcm_lib_free_pages(substream);
+#endif
 }
 
-static int snd_card_loopback_pcm_open(struct snd_pcm_substream *substream)
+static int snd_card_loopback_open(struct snd_pcm_substream *substream)
 {
-	struct snd_pcm_runtime *runtime = substream->runtime;
+	int half;
+	struct snd_card_loopback *loopback;
 	snd_card_loopback_pcm_t *dpcm;
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	loopback = (struct snd_card_loopback *)substream->private_data;
 
+	if (0 == substream->pcm->device) {
+		if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream)
+			half = 1;
+		else
+			half = 0;
+	} else {
+		if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream)
+			half = 0;
+		else
+			half = 1;
+	}
+	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream) {
+		if (loopback->cables[substream->number][half].playback_busy)
+			return -EBUSY;
+	} else {
+		if (loopback->cables[substream->number][half].capture_busy)
+			return -EBUSY;
+	}
 	dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
 	if (dpcm == NULL)
 		return -ENOMEM;
 	init_timer(&dpcm->timer);
-	dpcm->timer.data = (unsigned long) dpcm;
-	dpcm->timer.function = snd_card_loopback_pcm_timer_function;
 	spin_lock_init(&dpcm->lock);
 	dpcm->substream = substream;
+	dpcm->timer.data = (unsigned long)dpcm;
+	dpcm->timer.function = snd_card_loopback_timer_function;
+	dpcm->cable = &loopback->cables[substream->number][half];
 	runtime->private_data = dpcm;
 	runtime->private_free = snd_card_loopback_runtime_free;
 	runtime->hw = snd_card_loopback_info;
+
+	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream) {
+		dpcm->cable->playback = substream;
+		dpcm->cable->playback_valid = 0;
+		dpcm->cable->playback_running = 0;
+		dpcm->cable->playback_busy = 1;
+		if (dpcm->cable->capture_valid)
+			runtime->hw = dpcm->cable->hw;
+		else
+			dpcm->cable->hw = snd_card_loopback_info;
+	} else {
+#ifdef SND_CARD_LOOPBACK_COPY_RINGBUFFER
+		dpcm->timer.function = snd_card_loopback_capture_timer_function;
+#endif
+		dpcm->cable->capture = substream;
+		dpcm->cable->capture_valid = 0;
+		dpcm->cable->capture_running = 0;
+		dpcm->cable->capture_busy = 1;
+		if (dpcm->cable->playback_valid)
+			runtime->hw = dpcm->cable->hw;
+		else
+			dpcm->cable->hw = snd_card_loopback_info;
+	}
+	return 0;
+}
+
+static int snd_card_loopback_close(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
+	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream) {
+		dpcm->cable->playback_valid = 0;
+		dpcm->cable->playback_running = 0;
+		dpcm->cable->playback_busy = 0;
+		dpcm->cable->playback = NULL;
+	} else {
+		dpcm->cable->capture_valid = 0;
+		dpcm->cable->capture_running = 0;
+		dpcm->cable->capture_busy = 0;
+		dpcm->cable->capture = NULL;
+	}
 	return 0;
 }
 
 static struct snd_pcm_ops snd_card_loopback_playback_ops = {
-	.open =			snd_card_loopback_pcm_open,
-	.close =		NULL,
+	.open =			snd_card_loopback_open,
+	.close =		snd_card_loopback_close,
 	.ioctl =		snd_pcm_lib_ioctl,
 	.hw_params =		snd_card_loopback_hw_params,
 	.hw_free =		snd_card_loopback_hw_free,
-	.prepare =		snd_card_loopback_playback_prepare,
+	.prepare =		snd_card_loopback_prepare,
 	.trigger =		snd_card_loopback_playback_trigger,
-	.pointer =		snd_card_loopback_playback_pointer,
+	.pointer =		snd_card_loopback_pointer,
 };
 
 static struct snd_pcm_ops snd_card_loopback_capture_ops = {
-	.open =			snd_card_loopback_pcm_open,
-	.close =		NULL,
+	.open =			snd_card_loopback_open,
+	.close =		snd_card_loopback_close,
 	.ioctl =		snd_pcm_lib_ioctl,
 	.hw_params =		snd_card_loopback_hw_params,
 	.hw_free =		snd_card_loopback_hw_free,
-	.prepare =		snd_card_loopback_capture_prepare,
+	.prepare =		snd_card_loopback_prepare,
 	.trigger =		snd_card_loopback_capture_trigger,
-	.pointer =		snd_card_loopback_capture_pointer,
+	.pointer =		snd_card_loopback_pointer,
 };
 
 static int __init snd_card_loopback_pcm(snd_card_loopback_t *loopback, int device, int substreams)
@@ -264,22 +499,27 @@
 	struct snd_pcm *pcm;
 	int err;
 
-	if ((err = snd_pcm_new(loopback->card, "Loopback PCM", device, substreams, substreams, &pcm)) < 0)
-		return err;
-	if (device == 0)
+	if (0 == device) {
+		if ((err = snd_pcm_new(loopback->card, "Loopback PCM", device, substreams, substreams, &pcm)) < 0)
+			return err;
 		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_card_loopback_playback_ops);
-	else
 		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_card_loopback_capture_ops);
+	} else {
+		if ((err = snd_pcm_new(loopback->card, "Loopback PCM", device, substreams, substreams, &pcm)) < 0)
+			return err;
+		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_card_loopback_playback_ops);
+		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_card_loopback_capture_ops);
+	}
 	pcm->private_data = loopback;
 	pcm->info_flags = 0;
 	strcpy(pcm->name, "Loopback PCM");
 	snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
-					      snd_dma_continuous_data(GFP_KERNEL),
-					      0, 64*1024);
+			snd_dma_continuous_data(GFP_KERNEL), 0, 64*1024);
+
 	return 0;
 }
 
-static int __init snd_card_loopback_new_mixer(snd_card_loopback_t * loopback)
+static int __init snd_card_loopback_new_mixer(snd_card_loopback_t *loopback)
 {
 	struct snd_card *card = loopback->card;
 
@@ -292,7 +532,7 @@
 {
 	struct snd_card *card;
 	struct snd_card_loopback *loopback;
-	int err;
+	int subdev, half, err;
 
 	if (!enable[dev])
 		return -ENODEV;
@@ -301,6 +541,21 @@
 	if (card == NULL)
 		return -ENOMEM;
 	loopback = (struct snd_card_loopback *)card->private_data;
+
+	for (subdev = 0; subdev < pcm_substreams[dev]; subdev++) {
+		for (half = 0; half < 2; half++) {
+			loopback->cables[subdev][half].playback = NULL;
+			loopback->cables[subdev][half].capture = NULL;
+			loopback->cables[subdev][half].playback_valid = 0;
+			loopback->cables[subdev][half].capture_valid = 0;
+			loopback->cables[subdev][half].playback_running = 0;
+			loopback->cables[subdev][half].capture_running = 0;
+			loopback->cables[subdev][half].playback_busy = 0;
+			loopback->cables[subdev][half].capture_busy = 0;
+			loopback->cables[subdev][half].pcm_buf_pos = 0;
+		}
+	}
+	
 	loopback->card = card;
 	if (pcm_substreams[dev] < 1)
 		pcm_substreams[dev] = 1;

[-- Attachment #3: Type: text/plain, Size: 347 bytes --]

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Re: [PATCH] make snd-aloop loopback device work

[Takashi Iwai]

At Wed, 20 Dec 2006 23:58:11 +0100,
Ahmet İnan wrote:
> 
> ive merged the previously mentioned 2 working implementations into one file
> and made them switchable thru preprocessor directives.
> the secure one is the default.
> 
> its now fullduplex, this means:
> 
> aplay -D hw:0,0 lala.wav
> ecasound -i:alsahw,0,1,0
> 
> works exactly the same like:
> 
> aplay -D hw:0,1 lala.wav
> ecasound -i:alsahw,0,0,0
> 
> it would be nice if it could be included in the tree, so that other ppl can
> test this and yell at me when something is wrong.
> 
> still need to workout this pcm_jiffies problem, but when its done then i will
> also provide an patch for dummy.c, couse it suffers the same problem on
> HZ > 100 kernels.

Thanks for the patch.  The changes look almost good to me.

One of my remaining concern in this code is the case where hw_params
are different on playback and capture sides.  Did you test that case?

Anyway, Jaroslav should have some ideas about the implementation, as
he initiated this driver...


Takashi

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Re: [PATCH] make snd-aloop loopback device work

[Ahmet İnan]

> Thanks for the patch.  The changes look almost good to me.
it still needs some refinement but imho its very usable now.

> One of my remaining concern in this code is the case where hw_params
> are different on playback and capture sides.  Did you test that case?
yes sure and this is why i have these 2 implementations .. the first one
doesnt need to have both hw_params same. only the second, which is still
not finished (memory leak on close) and is off by default. both work
wonderfully for me.

> Anyway, Jaroslav should have some ideas about the implementation, as
> he initiated this driver...
im always open for suggestions.

ahmet


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Re: [PATCH] make snd-aloop loopback device work

[Ahmet İnan]

[-- Attachment #1: Type: text/plain, Size: 1326 bytes --]

well i couldnt really sleep well so ive created one more patch ..

got the non-copying version finished and also solved the HZ>100 problem for
weird rates like 44100 :)

so there is no memory leak annymore, that im aware of.

removed the copying version tho, couse it was too much code and it
started to get real ugly while i was trying to get both versions working.
imho its not really worth keeping it, but will keep the version somewhere
around if annyone might be interested in it ..

tried also various apps, using mmap and rw in various combinations and it
just works. i only get every now and then an underrun / overrun. but im going
to investigate that as soon as i get started playing around with my
userspace app.

i also experienced something weird:
when using oss emulation and synchronizing at start trigger, the oss apps
behave very strange, like playing ffwd. alsa native apps behave correct.
this is why i have the SND_CARD_LOOPBACK_START_SYNC switch now, default is
not to sync .. will investigate that too, but for me that is not really an
issue, couse if i want better worst case latency, i use a smaller buffer size.

files:
http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-driver-1.0.13-aloop-ainan-patch.diff
http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/aloop-kernel.c

ahmet


[-- Attachment #2: alsa-driver-1.0.13-aloop-ainan-patch.diff --]
[-- Type: text/plain, Size: 19220 bytes --]

--- alsa-driver-1.0.13.orig/drivers/aloop-kernel.c	2006-09-29 13:40:29.000000000 +0200
+++ alsa-driver-1.0.13/drivers/aloop-kernel.c	2006-12-24 20:03:32.089723065 +0100
@@ -30,19 +30,25 @@
 #include <sound/pcm.h>
 #include <sound/initval.h>
 
+/* comment in to trash your kernel logfiles */
+/* #define SND_CARD_LOOPBACK_VERBOSE */
+/* comment in for synchronization on start trigger
+ * works well on alsa apps but bad on oss emulation */
+/* #define SND_CARD_LOOPBACK_START_SYNC */
+
 MODULE_AUTHOR("Jaroslav Kysela <perex@suse.cz>");
 MODULE_DESCRIPTION("A loopback soundcard");
 MODULE_LICENSE("GPL");
 MODULE_SUPPORTED_DEVICE("{{ALSA,Loopback soundcard}}");
 
-#define MAX_PCM_SUBSTREAMS	256
+#define MAX_PCM_SUBSTREAMS	8
 
 static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;	/* Index 0-MAX */
 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;	/* ID for this card */
 static int enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
 static int pcm_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 1};
 static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
-//static int midi_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 2};
+/* static int midi_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 2}; */
 
 module_param_array(index, int, NULL, 0444);
 MODULE_PARM_DESC(index, "Index value for loopback soundcard.");
@@ -53,31 +59,47 @@
 module_param_array(pcm_devs, int, NULL, 0444);
 MODULE_PARM_DESC(pcm_devs, "PCM devices # (0-4) for loopback driver.");
 module_param_array(pcm_substreams, int, NULL, 0444);
-MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-16) for loopback driver.");
-//module_param_array(midi_devs, int, NULL, 0444);
-//MODULE_PARM_DESC(midi_devs, "MIDI devices # (0-2) for loopback driver.");
+MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-8) for loopback driver.");
+/* module_param_array(midi_devs, int, NULL, 0444);
+ * MODULE_PARM_DESC(midi_devs, "MIDI devices # (0-2) for loopback driver."); */
+
+typedef struct snd_card_loopback_cable {
+	struct snd_pcm_substream *playback;
+	struct snd_pcm_substream *capture;
+	struct snd_dma_buffer *dma_buffer;
+	struct snd_pcm_hardware hw;
+	int playback_valid;
+	int capture_valid;
+	int playback_running;
+	int capture_running;
+	int playback_busy;
+	int capture_busy;
+} snd_card_loopback_cable_t;
 
 typedef struct snd_card_loopback {
 	struct snd_card *card;
+	struct snd_card_loopback_cable cables[MAX_PCM_SUBSTREAMS][2];
 } snd_card_loopback_t;
 
 typedef struct snd_card_loopback_pcm {
-	snd_card_loopback_t *loopback;
 	spinlock_t lock;
 	struct timer_list timer;
-	unsigned int pcm_size;
-	unsigned int pcm_count;
+	unsigned int pcm_1000_size;	/* 1000 * buffer size */
+	unsigned int pcm_1000_count;	/* 1000 * period size */
+	unsigned int pcm_size;		/* buffer size */
+	unsigned int pcm_count;		/* period size */
 	unsigned int pcm_bps;		/* bytes per second */
-	unsigned int pcm_jiffie;	/* bytes per one jiffie */
-	unsigned int pcm_irq_pos;	/* IRQ position */
-	unsigned int pcm_buf_pos;	/* position in buffer */
+	unsigned int pcm_1000_jiffie;	/* 1000 * bytes per one jiffie */
+	unsigned int pcm_1000_irq_pos;	/* 1000 * IRQ position */
+	unsigned int pcm_1000_buf_pos;	/* 1000 * position in buffer */
+	unsigned int pcm_period_pos;	/* period size aligned pos in buffer */
 	struct snd_pcm_substream *substream;
+	struct snd_card_loopback_cable *cable;
 } snd_card_loopback_pcm_t;
 
 static struct snd_card *snd_loopback_cards[SNDRV_CARDS] = SNDRV_DEFAULT_PTR;
 
-
-static void snd_card_loopback_pcm_timer_start(struct snd_pcm_substream *substream)
+static void snd_card_loopback_timer_start(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
@@ -86,7 +108,7 @@
 	add_timer(&dpcm->timer);
 }
 
-static void snd_card_loopback_pcm_timer_stop(struct snd_pcm_substream *substream)
+static void snd_card_loopback_timer_stop(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
@@ -97,10 +119,28 @@
 static int snd_card_loopback_playback_trigger(struct snd_pcm_substream *substream,
 					   int cmd)
 {
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
+#ifdef SND_CARD_LOOPBACK_START_SYNC
+	snd_card_loopback_pcm_t *capture_dpcm;
+#endif
 	if (cmd == SNDRV_PCM_TRIGGER_START) {
-		snd_card_loopback_pcm_timer_start(substream);
+#ifdef SND_CARD_LOOPBACK_START_SYNC
+		if (dpcm->cable->capture_running) {
+			capture_dpcm = dpcm->cable->capture->runtime->private_data;
+			dpcm->pcm_1000_irq_pos = capture_dpcm->pcm_1000_irq_pos;
+			dpcm->pcm_1000_buf_pos = capture_dpcm->pcm_1000_buf_pos;
+			dpcm->pcm_period_pos = capture_dpcm->pcm_period_pos;
+		}
+#endif
+		dpcm->cable->playback_running = 1;
+		snd_card_loopback_timer_start(substream);
 	} else if (cmd == SNDRV_PCM_TRIGGER_STOP) {
-		snd_card_loopback_pcm_timer_stop(substream);
+		dpcm->cable->playback_running = 0;
+		snd_card_loopback_timer_stop(substream);
+		snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
+				bytes_to_samples(runtime, runtime->dma_bytes));
+
 	} else {
 		return -EINVAL;
 	}
@@ -110,20 +150,36 @@
 static int snd_card_loopback_capture_trigger(struct snd_pcm_substream *substream,
 					  int cmd)
 {
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
+#ifdef SND_CARD_LOOPBACK_START_SYNC
+	snd_card_loopback_pcm_t *playback_dpcm;
+#endif
 	if (cmd == SNDRV_PCM_TRIGGER_START) {
-		snd_card_loopback_pcm_timer_start(substream);
+#ifdef SND_CARD_LOOPBACK_START_SYNC
+		if (dpcm->cable->playback_running) {
+			playback_dpcm = dpcm->cable->playback->runtime->private_data;
+			dpcm->pcm_1000_irq_pos = playback_dpcm->pcm_1000_irq_pos;
+			dpcm->pcm_1000_buf_pos = playback_dpcm->pcm_1000_buf_pos;
+			dpcm->pcm_period_pos = playback_dpcm->pcm_period_pos;
+		}
+#endif
+		dpcm->cable->capture_running = 1;
+		snd_card_loopback_timer_start(substream);
 	} else if (cmd == SNDRV_PCM_TRIGGER_STOP) {
-		snd_card_loopback_pcm_timer_stop(substream);
+		dpcm->cable->capture_running = 0;
+		snd_card_loopback_timer_stop(substream);
 	} else {
 		return -EINVAL;
 	}
 	return 0;
 }
 
-static int snd_card_loopback_pcm_prepare(struct snd_pcm_substream *substream)
+static int snd_card_loopback_prepare(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
+	snd_card_loopback_cable_t *cable = dpcm->cable;
 	unsigned int bps;
 
 	bps = runtime->rate * runtime->channels;
@@ -132,55 +188,77 @@
 	if (bps <= 0)
 		return -EINVAL;
 	dpcm->pcm_bps = bps;
-	dpcm->pcm_jiffie = bps / HZ;
-	dpcm->pcm_size = snd_pcm_lib_buffer_bytes(substream);
-	dpcm->pcm_count = snd_pcm_lib_period_bytes(substream);
-	dpcm->pcm_irq_pos = 0;
-	dpcm->pcm_buf_pos = 0;
-	return 0;
-}
+	dpcm->pcm_1000_jiffie = (1000 * bps) / HZ;
+	dpcm->pcm_size = frames_to_bytes(runtime, runtime->buffer_size);
+	dpcm->pcm_count = frames_to_bytes(runtime, runtime->period_size);
+	dpcm->pcm_1000_size = 1000 * frames_to_bytes(runtime, runtime->buffer_size);
+	dpcm->pcm_1000_count = 1000 * frames_to_bytes(runtime, runtime->period_size);
+	dpcm->pcm_1000_irq_pos = 0;
+	dpcm->pcm_1000_buf_pos = 0;
+	dpcm->pcm_period_pos = 0;
+
+	cable->hw.formats = (1ULL << runtime->format);
+	cable->hw.rate_min = runtime->rate;
+	cable->hw.rate_max = runtime->rate;
+	cable->hw.channels_min = runtime->channels;
+	cable->hw.channels_max = runtime->channels;
+	cable->hw.buffer_bytes_max = frames_to_bytes(runtime, runtime->buffer_size);
+	cable->hw.period_bytes_min = frames_to_bytes(runtime, runtime->period_size);
+	cable->hw.period_bytes_max = frames_to_bytes(runtime, runtime->period_size);
+	cable->hw.periods_min = runtime->periods;
+	cable->hw.periods_max = runtime->periods;
 
-static int snd_card_loopback_playback_prepare(struct snd_pcm_substream *substream)
-{
-	return snd_card_loopback_pcm_prepare(substream);
-}
+	snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
+			bytes_to_samples(runtime, runtime->dma_bytes));
 
-static int snd_card_loopback_capture_prepare(struct snd_pcm_substream *substream)
-{
-	return snd_card_loopback_pcm_prepare(substream);
+	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream)
+		cable->playback_valid = 1;
+	else
+		cable->capture_valid = 1;
+
+#ifdef SND_CARD_LOOPBACK_VERBOSE
+	printk(KERN_INFO "snd-aloop(c%dd%ds%d%c): frq=%d chs=%d fmt=%d buf=%d per=%d pers=%d\n",
+			substream->pcm->card->number,
+			substream->pcm->device,
+			substream->stream,
+			(SNDRV_PCM_STREAM_PLAYBACK == substream->stream ? 'p' : 'c'),
+			runtime->rate,
+			runtime->channels,
+			snd_pcm_format_width(runtime->format),
+			frames_to_bytes(runtime, runtime->buffer_size),
+			frames_to_bytes(runtime, runtime->period_size),
+			runtime->periods);
+#endif
+	return 0;
 }
 
-static void snd_card_loopback_pcm_timer_function(unsigned long data)
+static void snd_card_loopback_timer_function(unsigned long data)
 {
 	snd_card_loopback_pcm_t *dpcm = (snd_card_loopback_pcm_t *)data;
 	
 	dpcm->timer.expires = 1 + jiffies;
 	add_timer(&dpcm->timer);
 	spin_lock_irq(&dpcm->lock);
-	dpcm->pcm_irq_pos += dpcm->pcm_jiffie;
-	dpcm->pcm_buf_pos += dpcm->pcm_jiffie;
-	dpcm->pcm_buf_pos %= dpcm->pcm_size;
-	if (dpcm->pcm_irq_pos >= dpcm->pcm_count) {
-		dpcm->pcm_irq_pos %= dpcm->pcm_count;
+
+	dpcm->pcm_1000_irq_pos += dpcm->pcm_1000_jiffie;
+	dpcm->pcm_1000_buf_pos += dpcm->pcm_1000_jiffie;
+	dpcm->pcm_1000_buf_pos %= dpcm->pcm_1000_size;
+	if (dpcm->pcm_1000_irq_pos >= dpcm->pcm_1000_count) {
+		dpcm->pcm_1000_irq_pos %= dpcm->pcm_1000_count;
+		dpcm->pcm_period_pos += dpcm->pcm_count;
+		dpcm->pcm_period_pos %= dpcm->pcm_size;
+		spin_unlock_irq(&dpcm->lock);	
 		snd_pcm_period_elapsed(dpcm->substream);
+	} else {
+		spin_unlock_irq(&dpcm->lock);
 	}
-	spin_unlock_irq(&dpcm->lock);	
 }
 
-static snd_pcm_uframes_t snd_card_loopback_playback_pointer(struct snd_pcm_substream *substream)
+static snd_pcm_uframes_t snd_card_loopback_pointer(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
-
-	return bytes_to_frames(runtime, dpcm->pcm_buf_pos);
-}
-
-static snd_pcm_uframes_t snd_card_loopback_capture_pointer(struct snd_pcm_substream *substream)
-{
-	struct snd_pcm_runtime *runtime = substream->runtime;
-	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
-
-	return bytes_to_frames(runtime, dpcm->pcm_buf_pos);
+	return bytes_to_frames(runtime, dpcm->pcm_period_pos);
 }
 
 static struct snd_pcm_hardware snd_card_loopback_info =
@@ -188,16 +266,16 @@
 	.info =			(SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
 				 SNDRV_PCM_INFO_MMAP_VALID),
 	.formats =		(SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S32_LE),
-	.rates =		SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_192000,
-	.rate_min =		5500,
+	.rates =		(SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_192000),
+	.rate_min =		8000,
 	.rate_max =		192000,
 	.channels_min =		1,
 	.channels_max =		32,
-	.buffer_bytes_max =	1024 * 1024,
-	.period_bytes_min =	32,
-	.period_bytes_max =	128 * 1024,
+	.buffer_bytes_max =	64 * 1024,
+	.period_bytes_min =	64,
+	.period_bytes_max =	64 * 1024,
 	.periods_min =		1,
-	.periods_max =		16,
+	.periods_max =		1024,
 	.fifo_size =		0,
 };
 
@@ -210,53 +288,156 @@
 static int snd_card_loopback_hw_params(struct snd_pcm_substream *substream,
 				    struct snd_pcm_hw_params *hw_params)
 {
-	return snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(hw_params));
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
+	struct snd_dma_buffer *dmab = NULL;
+	if (NULL == dpcm->cable->dma_buffer) {
+#ifdef SND_CARD_LOOPBACK_VERBOSE
+		printk(KERN_INFO "snd-aloop: allocating dma buffer\n");
+#endif
+		dmab = kzalloc(sizeof(*dmab), GFP_KERNEL);
+		if (NULL == dmab)
+			return -ENOMEM;
+		
+		if (snd_dma_alloc_pages(SNDRV_DMA_TYPE_CONTINUOUS,
+					snd_dma_continuous_data(GFP_KERNEL),
+					params_buffer_bytes(hw_params),
+					dmab) < 0) {
+			kfree(dmab);
+			return -ENOMEM;
+		}
+		dpcm->cable->dma_buffer = dmab;
+	}
+	snd_pcm_set_runtime_buffer(substream, dpcm->cable->dma_buffer);
+	return 0;
 }
 
 static int snd_card_loopback_hw_free(struct snd_pcm_substream *substream)
 {
-	return snd_pcm_lib_free_pages(substream);
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
+	snd_card_loopback_cable_t *cable = dpcm->cable;
+
+	snd_pcm_set_runtime_buffer(substream, NULL);
+
+	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream) {
+		if (cable->capture_busy)
+			return 0;
+	} else {
+		if (cable->playback_busy)
+			return 0;
+	}
+
+	if (NULL == cable->dma_buffer)
+		return 0;
+
+#ifdef SND_CARD_LOOPBACK_VERBOSE
+	printk(KERN_INFO "snd-aloop: freeing dma buffer\n");
+#endif
+	snd_dma_free_pages(cable->dma_buffer);
+	kfree(cable->dma_buffer);
+	cable->dma_buffer = NULL;
+	return 0;
 }
 
-static int snd_card_loopback_pcm_open(struct snd_pcm_substream *substream)
+static int snd_card_loopback_open(struct snd_pcm_substream *substream)
 {
-	struct snd_pcm_runtime *runtime = substream->runtime;
+	int half;
 	snd_card_loopback_pcm_t *dpcm;
+	struct snd_card_loopback *loopback = substream->private_data;
+	struct snd_pcm_runtime *runtime = substream->runtime;
 
+	if (0 == substream->pcm->device) {
+		if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream)
+			half = 1;
+		else
+			half = 0;
+	} else {
+		if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream)
+			half = 0;
+		else
+			half = 1;
+	}
+	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream) {
+		if (loopback->cables[substream->number][half].playback_busy)
+			return -EBUSY;
+	} else {
+		if (loopback->cables[substream->number][half].capture_busy)
+			return -EBUSY;
+	}
 	dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
 	if (dpcm == NULL)
 		return -ENOMEM;
 	init_timer(&dpcm->timer);
-	dpcm->timer.data = (unsigned long) dpcm;
-	dpcm->timer.function = snd_card_loopback_pcm_timer_function;
 	spin_lock_init(&dpcm->lock);
 	dpcm->substream = substream;
+	dpcm->timer.data = (unsigned long)dpcm;
+	dpcm->timer.function = snd_card_loopback_timer_function;
+	dpcm->cable = &loopback->cables[substream->number][half];
 	runtime->private_data = dpcm;
 	runtime->private_free = snd_card_loopback_runtime_free;
 	runtime->hw = snd_card_loopback_info;
+
+	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream) {
+		dpcm->cable->playback = substream;
+		dpcm->cable->playback_valid = 0;
+		dpcm->cable->playback_running = 0;
+		dpcm->cable->playback_busy = 1;
+		if (dpcm->cable->capture_valid)
+			runtime->hw = dpcm->cable->hw;
+		else
+			dpcm->cable->hw = snd_card_loopback_info;
+	} else {
+		dpcm->cable->capture = substream;
+		dpcm->cable->capture_valid = 0;
+		dpcm->cable->capture_running = 0;
+		dpcm->cable->capture_busy = 1;
+		if (dpcm->cable->playback_valid)
+			runtime->hw = dpcm->cable->hw;
+		else
+			dpcm->cable->hw = snd_card_loopback_info;
+	}
+	return 0;
+}
+
+static int snd_card_loopback_close(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
+	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream) {
+		dpcm->cable->playback_valid = 0;
+		dpcm->cable->playback_running = 0;
+		dpcm->cable->playback_busy = 0;
+		dpcm->cable->playback = NULL;
+	} else {
+		dpcm->cable->capture_valid = 0;
+		dpcm->cable->capture_running = 0;
+		dpcm->cable->capture_busy = 0;
+		dpcm->cable->capture = NULL;
+	}
 	return 0;
 }
 
 static struct snd_pcm_ops snd_card_loopback_playback_ops = {
-	.open =			snd_card_loopback_pcm_open,
-	.close =		NULL,
+	.open =			snd_card_loopback_open,
+	.close =		snd_card_loopback_close,
 	.ioctl =		snd_pcm_lib_ioctl,
 	.hw_params =		snd_card_loopback_hw_params,
 	.hw_free =		snd_card_loopback_hw_free,
-	.prepare =		snd_card_loopback_playback_prepare,
+	.prepare =		snd_card_loopback_prepare,
 	.trigger =		snd_card_loopback_playback_trigger,
-	.pointer =		snd_card_loopback_playback_pointer,
+	.pointer =		snd_card_loopback_pointer,
 };
 
 static struct snd_pcm_ops snd_card_loopback_capture_ops = {
-	.open =			snd_card_loopback_pcm_open,
-	.close =		NULL,
+	.open =			snd_card_loopback_open,
+	.close =		snd_card_loopback_close,
 	.ioctl =		snd_pcm_lib_ioctl,
 	.hw_params =		snd_card_loopback_hw_params,
 	.hw_free =		snd_card_loopback_hw_free,
-	.prepare =		snd_card_loopback_capture_prepare,
+	.prepare =		snd_card_loopback_prepare,
 	.trigger =		snd_card_loopback_capture_trigger,
-	.pointer =		snd_card_loopback_capture_pointer,
+	.pointer =		snd_card_loopback_pointer,
 };
 
 static int __init snd_card_loopback_pcm(snd_card_loopback_t *loopback, int device, int substreams)
@@ -264,22 +445,24 @@
 	struct snd_pcm *pcm;
 	int err;
 
-	if ((err = snd_pcm_new(loopback->card, "Loopback PCM", device, substreams, substreams, &pcm)) < 0)
-		return err;
-	if (device == 0)
+	if (0 == device) {
+		if ((err = snd_pcm_new(loopback->card, "Loopback PCM", device, substreams, substreams, &pcm)) < 0)
+			return err;
 		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_card_loopback_playback_ops);
-	else
 		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_card_loopback_capture_ops);
+	} else {
+		if ((err = snd_pcm_new(loopback->card, "Loopback PCM", device, substreams, substreams, &pcm)) < 0)
+			return err;
+		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_card_loopback_playback_ops);
+		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_card_loopback_capture_ops);
+	}
 	pcm->private_data = loopback;
 	pcm->info_flags = 0;
 	strcpy(pcm->name, "Loopback PCM");
-	snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
-					      snd_dma_continuous_data(GFP_KERNEL),
-					      0, 64*1024);
 	return 0;
 }
 
-static int __init snd_card_loopback_new_mixer(snd_card_loopback_t * loopback)
+static int __init snd_card_loopback_new_mixer(snd_card_loopback_t *loopback)
 {
 	struct snd_card *card = loopback->card;
 
@@ -292,7 +475,7 @@
 {
 	struct snd_card *card;
 	struct snd_card_loopback *loopback;
-	int err;
+	int subdev, half, err;
 
 	if (!enable[dev])
 		return -ENODEV;
@@ -301,6 +484,21 @@
 	if (card == NULL)
 		return -ENOMEM;
 	loopback = (struct snd_card_loopback *)card->private_data;
+
+	for (subdev = 0; subdev < pcm_substreams[dev]; subdev++) {
+		for (half = 0; half < 2; half++) {
+			loopback->cables[subdev][half].playback = NULL;
+			loopback->cables[subdev][half].capture = NULL;
+			loopback->cables[subdev][half].dma_buffer = NULL;
+			loopback->cables[subdev][half].playback_valid = 0;
+			loopback->cables[subdev][half].capture_valid = 0;
+			loopback->cables[subdev][half].playback_running = 0;
+			loopback->cables[subdev][half].capture_running = 0;
+			loopback->cables[subdev][half].playback_busy = 0;
+			loopback->cables[subdev][half].capture_busy = 0;
+		}
+	}
+	
 	loopback->card = card;
 	if (pcm_substreams[dev] < 1)
 		pcm_substreams[dev] = 1;

[-- Attachment #3: Type: text/plain, Size: 347 bytes --]

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_______________________________________________
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Alsa-devel@lists.sourceforge.net
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Re: [PATCH] make snd-aloop loopback device work

[Takashi Iwai]

At Thu, 28 Dec 2006 03:10:58 +0100,
Ahmet İnan wrote:
> 
> well i couldnt really sleep well so ive created one more patch ..
> 
> got the non-copying version finished and also solved the HZ>100 problem for
> weird rates like 44100 :)
> 
> so there is no memory leak annymore, that im aware of.
> 
> removed the copying version tho, couse it was too much code and it
> started to get real ugly while i was trying to get both versions working.
> imho its not really worth keeping it, but will keep the version somewhere
> around if annyone might be interested in it ..
> 
> tried also various apps, using mmap and rw in various combinations and it
> just works. i only get every now and then an underrun / overrun. but im going
> to investigate that as soon as i get started playing around with my
> userspace app.
> 
> i also experienced something weird:
> when using oss emulation and synchronizing at start trigger, the oss apps
> behave very strange, like playing ffwd. alsa native apps behave correct.
> this is why i have the SND_CARD_LOOPBACK_START_SYNC switch now, default is
> not to sync .. will investigate that too, but for me that is not really an
> issue, couse if i want better worst case latency, i use a smaller buffer size.
> 
> files:
> http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-driver-1.0.13-aloop-ainan-patch.diff
> http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/aloop-kernel.c

OK, I'd like to commit your patch to HG tree.  The driver is more or
less experimental.  Do you have more newer version?

Anyway, please give a proper changelog and a sign-off to commit.

Thanks,


Takashi

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Re: [PATCH] make snd-aloop loopback device work

[Ahmet İnan]

[-- Attachment #1: Type: text/plain, Size: 1785 bytes --]

> OK, I'd like to commit your patch to HG tree.  The driver is more or
> less experimental.  Do you have more newer version?
yes, but its only a minor change. i hopefully will have some time soon so that
i can investigate more problems. but currently its ok with me.

> Anyway, please give a proper changelog and a sign-off to commit.
i would include this text below in some form at least once somewhere, to make
the usage of the loopback device clear.

=====================================================================
Summary: make snd-aloop loopback device work
=====================================================================
Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>
=====================================================================
the snd-aloop device is a full-duplex loopback device, that can
be used to connect 2 apps together, so that each apps output
gets the input of the other app.

the first app forces the second app to use its settings, so
no rate, format or channel number conversion is done.

examples (hw:0 is loopback, !default is real soundcard / dmix):

capture output from other apps to hdd:
aplay -D hw:0,0 play.wav
arecord -D hw:0,1 record.wav

the same:
aplay -D hw:0,1 play.wav
arecord -D hw:0,0 record.wav

or have more fun:
ecasound -f:16,2,48000 -i:alsahw,0,1,0 &
ecasound -f:16,2,48000 -i:alsahw,0,1,1 &
ecasound -f:16,2,48000 -i:alsahw,0,1,2 &
...
now open up to 8 oss apps _without_ aoss, sit back and relax.
=====================================================================

files:
http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-driver-1.0.13-aloop-ainan-patch.diff
http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/aloop-kernel.c

ahmet


[-- Attachment #2: alsa-driver-1.0.13-aloop-ainan-patch.diff --]
[-- Type: text/plain, Size: 19314 bytes --]

--- alsa-driver-1.0.13.orig/drivers/aloop-kernel.c	2006-09-29 13:40:29.000000000 +0200
+++ alsa-driver-1.0.13/drivers/aloop-kernel.c	2007-01-16 13:32:07.709561155 +0100
@@ -30,19 +30,25 @@
 #include <sound/pcm.h>
 #include <sound/initval.h>
 
+/* comment in to trash your kernel logfiles */
+/* #define SND_CARD_LOOPBACK_VERBOSE */
+/* comment in for synchronization on start trigger
+ * works well on alsa apps but bad on oss emulation */
+/* #define SND_CARD_LOOPBACK_START_SYNC */
+
 MODULE_AUTHOR("Jaroslav Kysela <perex@suse.cz>");
 MODULE_DESCRIPTION("A loopback soundcard");
 MODULE_LICENSE("GPL");
 MODULE_SUPPORTED_DEVICE("{{ALSA,Loopback soundcard}}");
 
-#define MAX_PCM_SUBSTREAMS	256
+#define MAX_PCM_SUBSTREAMS	8
 
 static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;	/* Index 0-MAX */
 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;	/* ID for this card */
 static int enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
 static int pcm_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 1};
 static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
-//static int midi_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 2};
+/* static int midi_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 2}; */
 
 module_param_array(index, int, NULL, 0444);
 MODULE_PARM_DESC(index, "Index value for loopback soundcard.");
@@ -53,31 +59,49 @@
 module_param_array(pcm_devs, int, NULL, 0444);
 MODULE_PARM_DESC(pcm_devs, "PCM devices # (0-4) for loopback driver.");
 module_param_array(pcm_substreams, int, NULL, 0444);
-MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-16) for loopback driver.");
-//module_param_array(midi_devs, int, NULL, 0444);
-//MODULE_PARM_DESC(midi_devs, "MIDI devices # (0-2) for loopback driver.");
+MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-8) for loopback driver.");
+/* module_param_array(midi_devs, int, NULL, 0444);
+ * MODULE_PARM_DESC(midi_devs, "MIDI devices # (0-2) for loopback driver."); */
+
+typedef struct snd_card_loopback_cable {
+	struct snd_pcm_substream *playback;
+	struct snd_pcm_substream *capture;
+	struct snd_dma_buffer *dma_buffer;
+	struct snd_pcm_hardware hw;
+	int playback_valid;
+	int capture_valid;
+	int playback_running;
+	int capture_running;
+	int playback_busy;
+	int capture_busy;
+} snd_card_loopback_cable_t;
 
 typedef struct snd_card_loopback {
 	struct snd_card *card;
+	struct snd_card_loopback_cable cables[MAX_PCM_SUBSTREAMS][2];
 } snd_card_loopback_t;
 
 typedef struct snd_card_loopback_pcm {
 	snd_card_loopback_t *loopback;
 	spinlock_t lock;
 	struct timer_list timer;
+	int stream;
+	unsigned int pcm_1000_size;
+	unsigned int pcm_1000_count;
 	unsigned int pcm_size;
 	unsigned int pcm_count;
 	unsigned int pcm_bps;		/* bytes per second */
-	unsigned int pcm_jiffie;	/* bytes per one jiffie */
-	unsigned int pcm_irq_pos;	/* IRQ position */
-	unsigned int pcm_buf_pos;	/* position in buffer */
+	unsigned int pcm_1000_jiffie;	/* 1000 * bytes per one jiffie */
+	unsigned int pcm_1000_irq_pos;	/* IRQ position */
+	unsigned int pcm_1000_buf_pos;	/* position in buffer */
+	unsigned int pcm_period_pos;	/* period aligned pos in buffer */
 	struct snd_pcm_substream *substream;
+	struct snd_card_loopback_cable *cable;
 } snd_card_loopback_pcm_t;
 
 static struct snd_card *snd_loopback_cards[SNDRV_CARDS] = SNDRV_DEFAULT_PTR;
 
-
-static void snd_card_loopback_pcm_timer_start(struct snd_pcm_substream *substream)
+static void snd_card_loopback_timer_start(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
@@ -86,7 +110,7 @@
 	add_timer(&dpcm->timer);
 }
 
-static void snd_card_loopback_pcm_timer_stop(struct snd_pcm_substream *substream)
+static void snd_card_loopback_timer_stop(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
@@ -97,10 +121,28 @@
 static int snd_card_loopback_playback_trigger(struct snd_pcm_substream *substream,
 					   int cmd)
 {
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
+#ifdef SND_CARD_LOOPBACK_START_SYNC
+	snd_card_loopback_pcm_t *capture_dpcm;
+#endif
 	if (cmd == SNDRV_PCM_TRIGGER_START) {
-		snd_card_loopback_pcm_timer_start(substream);
+#ifdef SND_CARD_LOOPBACK_START_SYNC
+		if (dpcm->cable->capture_running) {
+			capture_dpcm = dpcm->cable->capture->runtime->private_data;
+			dpcm->pcm_1000_irq_pos = capture_dpcm->pcm_1000_irq_pos;
+			dpcm->pcm_1000_buf_pos = capture_dpcm->pcm_1000_buf_pos;
+			dpcm->pcm_period_pos = capture_dpcm->pcm_period_pos;
+		}
+#endif
+		dpcm->cable->playback_running = 1;
+		snd_card_loopback_timer_start(substream);
 	} else if (cmd == SNDRV_PCM_TRIGGER_STOP) {
-		snd_card_loopback_pcm_timer_stop(substream);
+		dpcm->cable->playback_running = 0;
+		snd_card_loopback_timer_stop(substream);
+		snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
+				bytes_to_samples(runtime, runtime->dma_bytes));
+
 	} else {
 		return -EINVAL;
 	}
@@ -110,20 +152,36 @@
 static int snd_card_loopback_capture_trigger(struct snd_pcm_substream *substream,
 					  int cmd)
 {
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
+#ifdef SND_CARD_LOOPBACK_START_SYNC
+	snd_card_loopback_pcm_t *playback_dpcm;
+#endif
 	if (cmd == SNDRV_PCM_TRIGGER_START) {
-		snd_card_loopback_pcm_timer_start(substream);
+#ifdef SND_CARD_LOOPBACK_START_SYNC
+		if (dpcm->cable->playback_running) {
+			playback_dpcm = dpcm->cable->playback->runtime->private_data;
+			dpcm->pcm_1000_irq_pos = playback_dpcm->pcm_1000_irq_pos;
+			dpcm->pcm_1000_buf_pos = playback_dpcm->pcm_1000_buf_pos;
+			dpcm->pcm_period_pos = playback_dpcm->pcm_period_pos;
+		}
+#endif
+		dpcm->cable->capture_running = 1;
+		snd_card_loopback_timer_start(substream);
 	} else if (cmd == SNDRV_PCM_TRIGGER_STOP) {
-		snd_card_loopback_pcm_timer_stop(substream);
+		dpcm->cable->capture_running = 0;
+		snd_card_loopback_timer_stop(substream);
 	} else {
 		return -EINVAL;
 	}
 	return 0;
 }
 
-static int snd_card_loopback_pcm_prepare(struct snd_pcm_substream *substream)
+static int snd_card_loopback_prepare(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
+	snd_card_loopback_cable_t *cable = dpcm->cable;
 	unsigned int bps;
 
 	bps = runtime->rate * runtime->channels;
@@ -132,55 +190,81 @@
 	if (bps <= 0)
 		return -EINVAL;
 	dpcm->pcm_bps = bps;
-	dpcm->pcm_jiffie = bps / HZ;
-	dpcm->pcm_size = snd_pcm_lib_buffer_bytes(substream);
-	dpcm->pcm_count = snd_pcm_lib_period_bytes(substream);
-	dpcm->pcm_irq_pos = 0;
-	dpcm->pcm_buf_pos = 0;
-	return 0;
-}
-
-static int snd_card_loopback_playback_prepare(struct snd_pcm_substream *substream)
-{
-	return snd_card_loopback_pcm_prepare(substream);
-}
+	dpcm->pcm_1000_jiffie = (1000 * bps) / HZ;
+	dpcm->pcm_size = frames_to_bytes(runtime, runtime->buffer_size);
+	dpcm->pcm_count = frames_to_bytes(runtime, runtime->period_size);
+	dpcm->pcm_1000_size = 1000 * frames_to_bytes(runtime, runtime->buffer_size);
+	dpcm->pcm_1000_count = 1000 * frames_to_bytes(runtime, runtime->period_size);
+	dpcm->pcm_1000_irq_pos = 0;
+	dpcm->pcm_1000_buf_pos = 0;
+	dpcm->pcm_period_pos = 0;
+
+	cable->hw.formats = (1ULL << runtime->format);
+	cable->hw.rate_min = runtime->rate;
+	cable->hw.rate_max = runtime->rate;
+	cable->hw.channels_min = runtime->channels;
+	cable->hw.channels_max = runtime->channels;
+	cable->hw.buffer_bytes_max = frames_to_bytes(runtime, runtime->buffer_size);
+	cable->hw.period_bytes_min = frames_to_bytes(runtime, runtime->period_size);
+	cable->hw.period_bytes_max = frames_to_bytes(runtime, runtime->period_size);
+	cable->hw.periods_min = runtime->periods;
+	cable->hw.periods_max = runtime->periods;
+
+	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream) {
+		snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
+				bytes_to_samples(runtime, runtime->dma_bytes));
+		cable->playback_valid = 1;
+	} else {
+		if (!cable->playback_running) {
+			snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
+					bytes_to_samples(runtime, runtime->dma_bytes));
+		}
+		cable->capture_valid = 1;
+	}
 
-static int snd_card_loopback_capture_prepare(struct snd_pcm_substream *substream)
-{
-	return snd_card_loopback_pcm_prepare(substream);
+#ifdef SND_CARD_LOOPBACK_VERBOSE
+	printk(KERN_INFO "snd-aloop(c%dd%ds%d%c): frq=%d chs=%d fmt=%d buf=%d per=%d pers=%d\n",
+			substream->pcm->card->number,
+			substream->pcm->device,
+			substream->stream,
+			(SNDRV_PCM_STREAM_PLAYBACK == substream->stream ? 'p' : 'c'),
+			runtime->rate,
+			runtime->channels,
+			snd_pcm_format_width(runtime->format),
+			frames_to_bytes(runtime, runtime->buffer_size),
+			frames_to_bytes(runtime, runtime->period_size),
+			runtime->periods);
+#endif
+	return 0;
 }
 
-static void snd_card_loopback_pcm_timer_function(unsigned long data)
+static void snd_card_loopback_timer_function(unsigned long data)
 {
 	snd_card_loopback_pcm_t *dpcm = (snd_card_loopback_pcm_t *)data;
 	
 	dpcm->timer.expires = 1 + jiffies;
 	add_timer(&dpcm->timer);
 	spin_lock_irq(&dpcm->lock);
-	dpcm->pcm_irq_pos += dpcm->pcm_jiffie;
-	dpcm->pcm_buf_pos += dpcm->pcm_jiffie;
-	dpcm->pcm_buf_pos %= dpcm->pcm_size;
-	if (dpcm->pcm_irq_pos >= dpcm->pcm_count) {
-		dpcm->pcm_irq_pos %= dpcm->pcm_count;
+
+	dpcm->pcm_1000_irq_pos += dpcm->pcm_1000_jiffie;
+	dpcm->pcm_1000_buf_pos += dpcm->pcm_1000_jiffie;
+	dpcm->pcm_1000_buf_pos %= dpcm->pcm_1000_size;
+	if (dpcm->pcm_1000_irq_pos >= dpcm->pcm_1000_count) {
+		dpcm->pcm_1000_irq_pos %= dpcm->pcm_1000_count;
+		dpcm->pcm_period_pos += dpcm->pcm_count;
+		dpcm->pcm_period_pos %= dpcm->pcm_size;
+		spin_unlock_irq(&dpcm->lock);	
 		snd_pcm_period_elapsed(dpcm->substream);
+	} else {
+		spin_unlock_irq(&dpcm->lock);
 	}
-	spin_unlock_irq(&dpcm->lock);	
 }
 
-static snd_pcm_uframes_t snd_card_loopback_playback_pointer(struct snd_pcm_substream *substream)
+static snd_pcm_uframes_t snd_card_loopback_pointer(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
-
-	return bytes_to_frames(runtime, dpcm->pcm_buf_pos);
-}
-
-static snd_pcm_uframes_t snd_card_loopback_capture_pointer(struct snd_pcm_substream *substream)
-{
-	struct snd_pcm_runtime *runtime = substream->runtime;
-	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
-
-	return bytes_to_frames(runtime, dpcm->pcm_buf_pos);
+	return bytes_to_frames(runtime, dpcm->pcm_period_pos);
 }
 
 static struct snd_pcm_hardware snd_card_loopback_info =
@@ -188,16 +272,16 @@
 	.info =			(SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
 				 SNDRV_PCM_INFO_MMAP_VALID),
 	.formats =		(SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S32_LE),
-	.rates =		SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_192000,
-	.rate_min =		5500,
+	.rates =		(SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_192000),
+	.rate_min =		8000,
 	.rate_max =		192000,
 	.channels_min =		1,
 	.channels_max =		32,
-	.buffer_bytes_max =	1024 * 1024,
-	.period_bytes_min =	32,
-	.period_bytes_max =	128 * 1024,
+	.buffer_bytes_max =	64 * 1024,
+	.period_bytes_min =	64,
+	.period_bytes_max =	64 * 1024,
 	.periods_min =		1,
-	.periods_max =		16,
+	.periods_max =		1024,
 	.fifo_size =		0,
 };
 
@@ -210,53 +294,158 @@
 static int snd_card_loopback_hw_params(struct snd_pcm_substream *substream,
 				    struct snd_pcm_hw_params *hw_params)
 {
-	return snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(hw_params));
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
+	struct snd_dma_buffer *dmab = NULL;
+	if (NULL == dpcm->cable->dma_buffer) {
+#ifdef SND_CARD_LOOPBACK_VERBOSE
+		printk(KERN_INFO "snd-aloop: allocating dma buffer\n");
+#endif
+		dmab = kzalloc(sizeof(*dmab), GFP_KERNEL);
+		if (NULL == dmab)
+			return -ENOMEM;
+		
+		if (snd_dma_alloc_pages(SNDRV_DMA_TYPE_CONTINUOUS,
+					snd_dma_continuous_data(GFP_KERNEL),
+					params_buffer_bytes(hw_params),
+					dmab) < 0) {
+			kfree(dmab);
+			return -ENOMEM;
+		}
+		dpcm->cable->dma_buffer = dmab;
+	}
+	snd_pcm_set_runtime_buffer(substream, dpcm->cable->dma_buffer);
+	return 0;
 }
 
 static int snd_card_loopback_hw_free(struct snd_pcm_substream *substream)
 {
-	return snd_pcm_lib_free_pages(substream);
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
+	snd_card_loopback_cable_t *cable = dpcm->cable;
+
+	snd_pcm_set_runtime_buffer(substream, NULL);
+
+	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream) {
+		if (cable->capture_busy)
+			return 0;
+	} else {
+		if (cable->playback_busy)
+			return 0;
+	}
+
+	if (NULL == cable->dma_buffer)
+		return 0;
+
+#ifdef SND_CARD_LOOPBACK_VERBOSE
+	printk(KERN_INFO "snd-aloop: freeing dma buffer\n");
+#endif
+	snd_dma_free_pages(cable->dma_buffer);
+	kfree(cable->dma_buffer);
+	cable->dma_buffer = NULL;
+	return 0;
 }
 
-static int snd_card_loopback_pcm_open(struct snd_pcm_substream *substream)
+static int snd_card_loopback_open(struct snd_pcm_substream *substream)
 {
-	struct snd_pcm_runtime *runtime = substream->runtime;
+	int half;
 	snd_card_loopback_pcm_t *dpcm;
+	struct snd_card_loopback *loopback = substream->private_data;
+	struct snd_pcm_runtime *runtime = substream->runtime;
 
+	if (0 == substream->pcm->device) {
+		if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream)
+			half = 1;
+		else
+			half = 0;
+	} else {
+		if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream)
+			half = 0;
+		else
+			half = 1;
+	}
+	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream) {
+		if (loopback->cables[substream->number][half].playback_busy)
+			return -EBUSY;
+	} else {
+		if (loopback->cables[substream->number][half].capture_busy)
+			return -EBUSY;
+	}
 	dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
 	if (dpcm == NULL)
 		return -ENOMEM;
 	init_timer(&dpcm->timer);
-	dpcm->timer.data = (unsigned long) dpcm;
-	dpcm->timer.function = snd_card_loopback_pcm_timer_function;
 	spin_lock_init(&dpcm->lock);
 	dpcm->substream = substream;
+	dpcm->loopback = loopback;
+	dpcm->timer.data = (unsigned long)dpcm;
+	dpcm->timer.function = snd_card_loopback_timer_function;
+	dpcm->cable = &loopback->cables[substream->number][half];
+	dpcm->stream = substream->stream;
 	runtime->private_data = dpcm;
 	runtime->private_free = snd_card_loopback_runtime_free;
 	runtime->hw = snd_card_loopback_info;
+
+	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream) {
+		dpcm->cable->playback = substream;
+		dpcm->cable->playback_valid = 0;
+		dpcm->cable->playback_running = 0;
+		dpcm->cable->playback_busy = 1;
+		if (dpcm->cable->capture_valid)
+			runtime->hw = dpcm->cable->hw;
+		else
+			dpcm->cable->hw = snd_card_loopback_info;
+	} else {
+		dpcm->cable->capture = substream;
+		dpcm->cable->capture_valid = 0;
+		dpcm->cable->capture_running = 0;
+		dpcm->cable->capture_busy = 1;
+		if (dpcm->cable->playback_valid)
+			runtime->hw = dpcm->cable->hw;
+		else
+			dpcm->cable->hw = snd_card_loopback_info;
+	}
+	return 0;
+}
+
+static int snd_card_loopback_close(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
+	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream) {
+		dpcm->cable->playback_valid = 0;
+		dpcm->cable->playback_running = 0;
+		dpcm->cable->playback_busy = 0;
+		dpcm->cable->playback = NULL;
+	} else {
+		dpcm->cable->capture_valid = 0;
+		dpcm->cable->capture_running = 0;
+		dpcm->cable->capture_busy = 0;
+		dpcm->cable->capture = NULL;
+	}
 	return 0;
 }
 
 static struct snd_pcm_ops snd_card_loopback_playback_ops = {
-	.open =			snd_card_loopback_pcm_open,
-	.close =		NULL,
+	.open =			snd_card_loopback_open,
+	.close =		snd_card_loopback_close,
 	.ioctl =		snd_pcm_lib_ioctl,
 	.hw_params =		snd_card_loopback_hw_params,
 	.hw_free =		snd_card_loopback_hw_free,
-	.prepare =		snd_card_loopback_playback_prepare,
+	.prepare =		snd_card_loopback_prepare,
 	.trigger =		snd_card_loopback_playback_trigger,
-	.pointer =		snd_card_loopback_playback_pointer,
+	.pointer =		snd_card_loopback_pointer,
 };
 
 static struct snd_pcm_ops snd_card_loopback_capture_ops = {
-	.open =			snd_card_loopback_pcm_open,
-	.close =		NULL,
+	.open =			snd_card_loopback_open,
+	.close =		snd_card_loopback_close,
 	.ioctl =		snd_pcm_lib_ioctl,
 	.hw_params =		snd_card_loopback_hw_params,
 	.hw_free =		snd_card_loopback_hw_free,
-	.prepare =		snd_card_loopback_capture_prepare,
+	.prepare =		snd_card_loopback_prepare,
 	.trigger =		snd_card_loopback_capture_trigger,
-	.pointer =		snd_card_loopback_capture_pointer,
+	.pointer =		snd_card_loopback_pointer,
 };
 
 static int __init snd_card_loopback_pcm(snd_card_loopback_t *loopback, int device, int substreams)
@@ -264,22 +453,24 @@
 	struct snd_pcm *pcm;
 	int err;
 
-	if ((err = snd_pcm_new(loopback->card, "Loopback PCM", device, substreams, substreams, &pcm)) < 0)
-		return err;
-	if (device == 0)
+	if (0 == device) {
+		if ((err = snd_pcm_new(loopback->card, "Loopback PCM", device, substreams, substreams, &pcm)) < 0)
+			return err;
 		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_card_loopback_playback_ops);
-	else
 		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_card_loopback_capture_ops);
+	} else {
+		if ((err = snd_pcm_new(loopback->card, "Loopback PCM", device, substreams, substreams, &pcm)) < 0)
+			return err;
+		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_card_loopback_playback_ops);
+		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_card_loopback_capture_ops);
+	}
 	pcm->private_data = loopback;
 	pcm->info_flags = 0;
 	strcpy(pcm->name, "Loopback PCM");
-	snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
-					      snd_dma_continuous_data(GFP_KERNEL),
-					      0, 64*1024);
 	return 0;
 }
 
-static int __init snd_card_loopback_new_mixer(snd_card_loopback_t * loopback)
+static int __init snd_card_loopback_new_mixer(snd_card_loopback_t *loopback)
 {
 	struct snd_card *card = loopback->card;
 
@@ -292,7 +483,7 @@
 {
 	struct snd_card *card;
 	struct snd_card_loopback *loopback;
-	int err;
+	int subdev, half, err;
 
 	if (!enable[dev])
 		return -ENODEV;
@@ -301,6 +492,21 @@
 	if (card == NULL)
 		return -ENOMEM;
 	loopback = (struct snd_card_loopback *)card->private_data;
+
+	for (subdev = 0; subdev < pcm_substreams[dev]; subdev++) {
+		for (half = 0; half < 2; half++) {
+			loopback->cables[subdev][half].playback = NULL;
+			loopback->cables[subdev][half].capture = NULL;
+			loopback->cables[subdev][half].dma_buffer = NULL;
+			loopback->cables[subdev][half].playback_valid = 0;
+			loopback->cables[subdev][half].capture_valid = 0;
+			loopback->cables[subdev][half].playback_running = 0;
+			loopback->cables[subdev][half].capture_running = 0;
+			loopback->cables[subdev][half].playback_busy = 0;
+			loopback->cables[subdev][half].capture_busy = 0;
+		}
+	}
+	
 	loopback->card = card;
 	if (pcm_substreams[dev] < 1)
 		pcm_substreams[dev] = 1;

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Re: [PATCH] make snd-aloop loopback device work

[Takashi Iwai]

At Wed, 17 Jan 2007 23:37:10 +0100,
Ahmet İnan wrote:
> 
> > OK, I'd like to commit your patch to HG tree.  The driver is more or
> > less experimental.  Do you have more newer version?
> yes, but its only a minor change. i hopefully will have some time soon so that
> i can investigate more problems. but currently its ok with me.
> 
> > Anyway, please give a proper changelog and a sign-off to commit.
> i would include this text below in some form at least once somewhere, to make
> the usage of the loopback device clear.

Thanks, I applied to HG tree now.


Takashi

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