ALSA: firewire-lib: use variable size of queue for isoc packets instead of fixed size

The number of packets in packet buffer has been fixed number (=48) since
first commit of ALSA IEC 61883-1/6 packet streaming engine.

This commit allows the engine to use variable number of packets in the
buffer. The size is calculated by a parameter in AMDTP domain structure
surely to store the number of events in the packets of buffer. Although
the value of parameter is expected to come from 'period size' parameter
of PCM substream, at present 48 is still used.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20191017155424.885-2-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 28 insertions, 17 deletions

diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c
index 838f695b20de..1f38729c8e74 100644
--- a/sound/firewire/amdtp-stream.c
+++ b/sound/firewire/amdtp-stream.c
@@ -54,7 +54,6 @@
 
 /* TODO: make these configurable */
 #define INTERRUPT_INTERVAL	16
-#define QUEUE_LENGTH		48
 
 // For iso header, tstamp and 2 CIP header.
 #define IR_CTX_HEADER_SIZE_CIP		16
@@ -451,7 +450,7 @@ static int queue_packet(struct amdtp_stream *s, struct fw_iso_packet *params)
 		goto end;
 	}
 
-	if (++s->packet_index >= QUEUE_LENGTH)
+	if (++s->packet_index >= s->queue_size)
 		s->packet_index = 0;
 end:
 	return err;
@@ -669,13 +668,14 @@ static inline u32 increment_cycle_count(u32 cycle, unsigned int addend)
 }
 
 // Align to actual cycle count for the packet which is going to be scheduled.
-// This module queued the same number of isochronous cycle as QUEUE_LENGTH to
-// skip isochronous cycle, therefore it's OK to just increment the cycle by
-// QUEUE_LENGTH for scheduled cycle.
-static inline u32 compute_it_cycle(const __be32 ctx_header_tstamp)
+// This module queued the same number of isochronous cycle as the size of queue
+// to kip isochronous cycle, therefore it's OK to just increment the cycle by
+// the size of queue for scheduled cycle.
+static inline u32 compute_it_cycle(const __be32 ctx_header_tstamp,
+				   unsigned int queue_size)
 {
 	u32 cycle = compute_cycle_count(ctx_header_tstamp);
-	return increment_cycle_count(cycle, QUEUE_LENGTH);
+	return increment_cycle_count(cycle, queue_size);
 }
 
 static int generate_device_pkt_descs(struct amdtp_stream *s,
@@ -689,7 +689,7 @@ static int generate_device_pkt_descs(struct amdtp_stream *s,
 
 	for (i = 0; i < packets; ++i) {
 		struct pkt_desc *desc = descs + i;
-		unsigned int index = (s->packet_index + i) % QUEUE_LENGTH;
+		unsigned int index = (s->packet_index + i) % s->queue_size;
 		unsigned int cycle;
 		unsigned int payload_length;
 		unsigned int data_blocks;
@@ -730,9 +730,9 @@ static void generate_ideal_pkt_descs(struct amdtp_stream *s,
 
 	for (i = 0; i < packets; ++i) {
 		struct pkt_desc *desc = descs + i;
-		unsigned int index = (s->packet_index + i) % QUEUE_LENGTH;
+		unsigned int index = (s->packet_index + i) % s->queue_size;
 
-		desc->cycle = compute_it_cycle(*ctx_header);
+		desc->cycle = compute_it_cycle(*ctx_header, s->queue_size);
 		desc->syt = calculate_syt(s, desc->cycle);
 		desc->data_blocks = calculate_data_blocks(s, desc->syt);
 
@@ -779,12 +779,15 @@ static void out_stream_callback(struct fw_iso_context *context, u32 tstamp,
 {
 	struct amdtp_stream *s = private_data;
 	const __be32 *ctx_header = header;
-	unsigned int packets = header_length / sizeof(*ctx_header);
+	unsigned int packets;
 	int i;
 
 	if (s->packet_index < 0)
 		return;
 
+	// Calculate the number of packets in buffer and check XRUN.
+	packets = header_length / sizeof(*ctx_header);
+
 	generate_ideal_pkt_descs(s, s->pkt_descs, ctx_header, packets);
 
 	process_ctx_payloads(s, s->pkt_descs, packets);
@@ -828,7 +831,7 @@ static void in_stream_callback(struct fw_iso_context *context, u32 tstamp,
 	if (s->packet_index < 0)
 		return;
 
-	// The number of packets in buffer.
+	// Calculate the number of packets in buffer and check XRUN.
 	packets = header_length / s->ctx_data.tx.ctx_header_size;
 
 	err = generate_device_pkt_descs(s, s->pkt_descs, ctx_header, packets);
@@ -874,7 +877,7 @@ static void amdtp_stream_first_callback(struct fw_iso_context *context,
 
 		context->callback.sc = in_stream_callback;
 	} else {
-		cycle = compute_it_cycle(*ctx_header);
+		cycle = compute_it_cycle(*ctx_header, s->queue_size);
 
 		context->callback.sc = out_stream_callback;
 	}
@@ -894,7 +897,8 @@ static void amdtp_stream_first_callback(struct fw_iso_context *context,
  * amdtp_stream_set_parameters() and it must be started before any PCM or MIDI
  * device can be started.
  */
-static int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed)
+static int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed,
+			      struct amdtp_domain *d)
 {
 	static const struct {
 		unsigned int data_block;
@@ -908,6 +912,7 @@ static int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed)
 		[CIP_SFC_88200]  = {  0,   67 },
 		[CIP_SFC_176400] = {  0,   67 },
 	};
+	unsigned int events_per_buffer = d->events_per_buffer;
 	unsigned int ctx_header_size;
 	unsigned int max_ctx_payload_size;
 	enum dma_data_direction dir;
@@ -953,7 +958,13 @@ static int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed)
 			max_ctx_payload_size -= IT_PKT_HEADER_SIZE_CIP;
 	}
 
-	err = iso_packets_buffer_init(&s->buffer, s->unit, QUEUE_LENGTH,
+	if (events_per_buffer == 0)
+		events_per_buffer = INTERRUPT_INTERVAL * 3;
+
+	s->queue_size = DIV_ROUND_UP(CYCLES_PER_SECOND * events_per_buffer,
+				     amdtp_rate_table[s->sfc]);
+
+	err = iso_packets_buffer_init(&s->buffer, s->unit, s->queue_size,
 				      max_ctx_payload_size, dir);
 	if (err < 0)
 		goto err_unlock;
@@ -981,7 +992,7 @@ static int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed)
 	else
 		s->tag = TAG_CIP;
 
-	s->pkt_descs = kcalloc(INTERRUPT_INTERVAL, sizeof(*s->pkt_descs),
+	s->pkt_descs = kcalloc(s->queue_size, sizeof(*s->pkt_descs),
 			       GFP_KERNEL);
 	if (!s->pkt_descs) {
 		err = -ENOMEM;
@@ -1196,7 +1207,7 @@ int amdtp_domain_start(struct amdtp_domain *d)
 	int err = 0;
 
 	list_for_each_entry(s, &d->streams, list) {
-		err = amdtp_stream_start(s, s->channel, s->speed);
+		err = amdtp_stream_start(s, s->channel, s->speed, d);
 		if (err < 0)
 			break;
 	}