Fix buffer size handling of direct plugins

Introduce "max_periods" option to specify the max number of periods
per buffer to each plugin.

- When max_periods = -1, the fixed buffer size as the slave size is
  used (old behavior).
- When max_periods = 0 (or 1), the number of periods is variable
  between 2 and the slave buffer size.
- When max_periods greater than 2 is given, it specifies the max
  periods of that pcm explicitly.

When no option is given in the PCM defintion, the value
"defaults.pcm.dmix_max_periods" is referred as default.
The default value is 0, as defined in alsa.conf.
You can override this in ~/.asoundrc or /etc/asound.conf as you like.

src/conf/alsa.conf

@@ -57,7 +57,7 @@ defaults.pcm.nonblock 1
 defaults.pcm.ipc_key 5678293
 defaults.pcm.ipc_gid audio
 defaults.pcm.ipc_perm 0660
-defaults.pcm.dmix_variable_buffer true
+defaults.pcm.dmix_max_periods 0
 defaults.pcm.front.card defaults.pcm.card
 defaults.pcm.front.device defaults.pcm.device
 defaults.pcm.rear.card defaults.pcm.card

src/conf/pcm/dmix.conf

@@ -92,9 +92,4 @@ pcm.!dmix {
 			default 16
 		}
 	}
-	# Allow apps different buffer sizes
-	variable_buffer_size {
-		@func refer
-		name defaults.pcm.dmix_variable_buffer
-	}
 }

src/pcm/pcm_direct.c

@@ -697,7 +697,7 @@ int snd_pcm_direct_hw_refine(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
 					   &dshare->shmptr->hw.period_time);
 	if (err < 0)
 		return err;
-	if (! dshare->variable_buffer_size) {
+	if (dshare->max_periods < 0) {
 		err = hw_param_interval_refine_one(params, SND_PCM_HW_PARAM_BUFFER_SIZE,
 						   &dshare->shmptr->hw.buffer_size);
 		if (err < 0)
@@ -711,13 +711,13 @@ int snd_pcm_direct_hw_refine(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
 				    (1<<SND_PCM_HW_PARAM_BUFFER_SIZE)|
 				    (1<<SND_PCM_HW_PARAM_BUFFER_TIME))) {
 		int changed;
+		unsigned int max_periods = dshare->max_periods;
+		if (max_periods < 2)
+			max_periods = dshare->slave_buffer_size / dshare->slave_period_size;
 		do {
 			changed = 0;
-			/* Set min/max size to [2:1024] since INT_MAX as the
-			 * upper-limit results in a too big buffer on some apps.
-			 */
 			err = hw_param_interval_refine_minmax(params, SND_PCM_HW_PARAM_PERIODS,
-							      2, 1024);
+							      2, max_periods);
 			if (err < 0)
 				return err;
 			changed |= err;
@@ -1382,17 +1382,19 @@ static int _snd_pcm_direct_get_slave_ipc_offset(snd_config_t *root,
 	return (direction << 1) + (device << 2) + (subdevice << 8) + (card << 12);
 }
 
-int snd_pcm_direct_get_slave_ipc_offset(snd_config_t *root,
+static int snd_pcm_direct_get_slave_ipc_offset(snd_config_t *root,
 					snd_config_t *sconf,
 					int direction)
 {
 	return _snd_pcm_direct_get_slave_ipc_offset(root, sconf, direction, 0);
 }
 
-int snd_pcm_direct_parse_open_conf(snd_config_t *conf, struct snd_pcm_direct_open_conf *rec)
+int snd_pcm_direct_parse_open_conf(snd_config_t *root, snd_config_t *conf,
+				   int stream, struct snd_pcm_direct_open_conf *rec)
 {
 	snd_config_iterator_t i, next;
 	int ipc_key_add_uid = 0;
+	snd_config_t *n;
 	int err;
 
 	rec->slave = NULL;
@@ -1401,10 +1403,18 @@ int snd_pcm_direct_parse_open_conf(snd_config_t *conf, struct snd_pcm_direct_ope
 	rec->ipc_perm = 0600;
 	rec->ipc_gid = -1;
 	rec->slowptr = 0;
-	rec->variable_buffer_size = 0;
+	rec->max_periods = 0;
+
+	/* read defaults */
+	if (snd_config_search(root, "defaults.pcm.dmix_max_periods", &n) >= 0) {
+		long val;
+		err = snd_config_get_integer(n, &val);
+		if (err >= 0)
+			rec->max_periods = val;
+	}
 
 	snd_config_for_each(i, next, conf) {
-		snd_config_t *n = snd_config_iterator_entry(i);
+		n = snd_config_iterator_entry(i);
 		const char *id;
 		if (snd_config_get_id(n, &id) < 0)
 			continue;
@@ -1488,11 +1498,12 @@ int snd_pcm_direct_parse_open_conf(snd_config_t *conf, struct snd_pcm_direct_ope
 			rec->slowptr = err;
 			continue;
 		}
-		if (strcmp(id, "variable_buffer_size") == 0) {
+		if (strcmp(id, "max_periods") == 0) {
-			err = snd_config_get_bool(n);
+			long val;
+			err = snd_config_get_integer(n, &val);
 			if (err < 0)
 				return err;
-			rec->variable_buffer_size = err;
+			rec->max_periods = val;
 			continue;
 		}
 		SNDERR("Unknown field %s", id);
@@ -1502,11 +1513,16 @@ int snd_pcm_direct_parse_open_conf(snd_config_t *conf, struct snd_pcm_direct_ope
 		SNDERR("slave is not defined");
 		return -EINVAL;
 	}
-	if (ipc_key_add_uid)
-		rec->ipc_key += getuid();
 	if (!rec->ipc_key) {
 		SNDERR("Unique IPC key is not defined");
 		return -EINVAL;
 	}
+	if (ipc_key_add_uid)
+		rec->ipc_key += getuid();
+	err = snd_pcm_direct_get_slave_ipc_offset(root, rec->slave, stream);
+	if (err < 0)
+		return err;
+	rec->ipc_key += err;
+
 	return 0;
 }

src/pcm/pcm_direct.h

@@ -117,7 +117,7 @@ struct snd_pcm_direct {
 	snd_timer_t *timer; 		/* timer used as poll_fd */
 	int interleaved;	 	/* we have interleaved buffer */
 	int slowptr;			/* use slow but more precise ptr updates */
-	int variable_buffer_size;	/* allow the variable buffer size */
+	int max_periods;		/* max periods (-1 = fixed periods, 0 = max buffer size) */
 	unsigned int channels;		/* client's channels */
 	unsigned int *bindings;
 	union {
@@ -187,7 +187,6 @@ int snd_pcm_direct_timer_stop(snd_pcm_direct_t *dmix);
 void snd_pcm_direct_clear_timer_queue(snd_pcm_direct_t *dmix);
 int snd_pcm_direct_set_timer_params(snd_pcm_direct_t *dmix);
 int snd_pcm_direct_open_secondary_client(snd_pcm_t **spcmp, snd_pcm_direct_t *dmix, const char *client_name);
-int snd_pcm_direct_get_slave_ipc_offset(snd_config_t *root, snd_config_t *sconf, int direction);
 
 int snd_timer_async(snd_timer_t *timer, int sig, pid_t pid);
 struct timespec snd_pcm_hw_fast_tstamp(snd_pcm_t *pcm);
@@ -197,9 +196,9 @@ struct snd_pcm_direct_open_conf {
 	mode_t ipc_perm;
 	int ipc_gid;
 	int slowptr;
-	int variable_buffer_size;
+	int max_periods;
 	snd_config_t *slave;
 	snd_config_t *bindings;
 };
 
-int snd_pcm_direct_parse_open_conf(snd_config_t *conf, struct snd_pcm_direct_open_conf *rec);
+int snd_pcm_direct_parse_open_conf(snd_config_t *root, snd_config_t *conf, int stream, struct snd_pcm_direct_open_conf *rec);

src/pcm/pcm_dmix.c

@@ -487,8 +487,7 @@ static int snd_pcm_dmix_prepare(snd_pcm_t *pcm)
 static void reset_slave_ptr(snd_pcm_t *pcm, snd_pcm_direct_t *dmix)
 {
 	dmix->slave_appl_ptr = dmix->slave_hw_ptr = *dmix->spcm->hw.ptr;
-	if (! dmix->variable_buffer_size ||
+	if (pcm->buffer_size > pcm->period_size * 2)
-	    pcm->buffer_size > pcm->period_size * 2)
 		return;
 	/* If we have too litte periods, better to align the start position
 	 * to the period boundary so that the interrupt can be handled properly
@@ -851,7 +850,7 @@ int snd_pcm_dmix_open(snd_pcm_t **pcmp, const char *name,
 	pcm->private_data = dmix;
 	dmix->state = SND_PCM_STATE_OPEN;
 	dmix->slowptr = opts->slowptr;
-	dmix->variable_buffer_size = opts->variable_buffer_size;
+	dmix->max_periods = opts->max_periods;
 	dmix->sync_ptr = snd_pcm_dmix_sync_ptr;
 
 	if (first_instance) {
@@ -1092,10 +1091,9 @@ int _snd_pcm_dmix_open(snd_pcm_t **pcmp, const char *name,
 	struct slave_params params;
 	struct snd_pcm_direct_open_conf dopen;
 	int bsize, psize;
-	int ipc_offset;
 	int err;
 
-	err = snd_pcm_direct_parse_open_conf(conf, &dopen);
+	err = snd_pcm_direct_parse_open_conf(root, conf, stream, &dopen);
 	if (err < 0)
 		return err;
 
@@ -1134,13 +1132,6 @@ int _snd_pcm_dmix_open(snd_pcm_t **pcmp, const char *name,
 	params.period_size = psize;
 	params.buffer_size = bsize;
 
-	ipc_offset = snd_pcm_direct_get_slave_ipc_offset(root, sconf, stream);
-	if (ipc_offset < 0) {
-		snd_config_delete(sconf);
-		return ipc_offset;
-	}
-	dopen.ipc_key += ipc_offset;
-
 	err = snd_pcm_dmix_open(pcmp, name, &dopen, &params,
 				root, sconf, stream, mode);
 	if (err < 0)

src/pcm/pcm_dshare.c

@@ -662,7 +662,7 @@ int snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
 	pcm->private_data = dshare;
 	dshare->state = SND_PCM_STATE_OPEN;
 	dshare->slowptr = opts->slowptr;
-	dshare->variable_buffer_size = opts->variable_buffer_size;
+	dshare->max_periods = opts->max_periods;
 	dshare->sync_ptr = snd_pcm_dshare_sync_ptr;
 
 	if (first_instance) {
@@ -835,10 +835,9 @@ int _snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
 	struct slave_params params;
 	struct snd_pcm_direct_open_conf dopen;
 	int bsize, psize;
-	int ipc_offset;
 	int err;
 
-	err = snd_pcm_direct_parse_open_conf(conf, &dopen);
+	err = snd_pcm_direct_parse_open_conf(root, conf, stream, &dopen);
 	if (err < 0)
 		return err;
 
@@ -869,13 +868,6 @@ int _snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
 	params.period_size = psize;
 	params.buffer_size = bsize;
 
-	ipc_offset = snd_pcm_direct_get_slave_ipc_offset(root, sconf, stream);
-	if (ipc_offset < 0) {
-		snd_config_delete(sconf);
-		return ipc_offset;
-	}
-	dopen.ipc_key += ipc_offset;
-
 	err = snd_pcm_dshare_open(pcmp, name, &dopen, &params,
 				  root, sconf, stream, mode);
 	if (err < 0)

src/pcm/pcm_dsnoop.c

@@ -544,7 +544,7 @@ int snd_pcm_dsnoop_open(snd_pcm_t **pcmp, const char *name,
 	pcm->private_data = dsnoop;
 	dsnoop->state = SND_PCM_STATE_OPEN;
 	dsnoop->slowptr = opts->slowptr;
-	dsnoop->variable_buffer_size = opts->variable_buffer_size;
+	dsnoop->max_periods = opts->max_periods;
 	dsnoop->sync_ptr = snd_pcm_dsnoop_sync_ptr;
 
 	if (first_instance) {
@@ -707,10 +707,9 @@ int _snd_pcm_dsnoop_open(snd_pcm_t **pcmp, const char *name,
 	struct slave_params params;
 	struct snd_pcm_direct_open_conf dopen;
 	int bsize, psize;
-	int ipc_offset;
 	int err;
 
-	err = snd_pcm_direct_parse_open_conf(conf, &dopen);
+	err = snd_pcm_direct_parse_open_conf(root, conf, stream, &dopen);
 	if (err < 0)
 		return err;
 
@@ -741,13 +740,6 @@ int _snd_pcm_dsnoop_open(snd_pcm_t **pcmp, const char *name,
 	params.period_size = psize;
 	params.buffer_size = bsize;
 
-	ipc_offset = snd_pcm_direct_get_slave_ipc_offset(root, sconf, stream);
-	if (ipc_offset < 0) {
-		snd_config_delete(sconf);
-		return ipc_offset;
-	}
-	dopen.ipc_key += ipc_offset;
-
 	err = snd_pcm_dsnoop_open(pcmp, name, &dopen, &params,
 				  root, sconf, stream, mode);
 	if (err < 0)