ALSA: firewire-lib: pool ideal sequence of syt offset and data block

In current implementation, sequence of syt offset and the number of data
blocks is generated when packets for outgoing stream are going to be
queued.

This commit generates and pools the sequence independently of the
processing of outgoing packets for future extension.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20200508043635.349339-10-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/amdtp-stream.c

@@ -905,14 +905,63 @@ static void in_stream_callback(struct fw_iso_context *context, u32 tstamp,
 	}
 }
 
+static void pool_ideal_seq_descs(struct amdtp_domain *d, unsigned int packets)
+{
+	struct amdtp_stream *irq_target = d->irq_target;
+	unsigned int seq_tail = d->seq_tail;
+	unsigned int seq_size = d->seq_size;
+	unsigned int min_avail;
+	struct amdtp_stream *s;
+
+	min_avail = d->seq_size;
+	list_for_each_entry(s, &d->streams, list) {
+		unsigned int seq_index;
+		unsigned int avail;
+
+		if (s->direction == AMDTP_IN_STREAM)
+			continue;
+
+		seq_index = s->ctx_data.rx.seq_index;
+		avail = d->seq_tail;
+		if (seq_index > avail)
+			avail += d->seq_size;
+		avail -= seq_index;
+
+		if (avail < min_avail)
+			min_avail = avail;
+	}
+
+	while (min_avail < packets) {
+		struct seq_desc *desc = d->seq_descs + seq_tail;
+
+		desc->syt_offset = calculate_syt_offset(&d->last_syt_offset,
+					&d->syt_offset_state, irq_target->sfc);
+		desc->data_blocks = calculate_data_blocks(&d->data_block_state,
+				!!(irq_target->flags & CIP_BLOCKING),
+				desc->syt_offset == CIP_SYT_NO_INFO,
+				irq_target->syt_interval, irq_target->sfc);
+
+		++seq_tail;
+		seq_tail %= seq_size;
+
+		++min_avail;
+	}
+
+	d->seq_tail = seq_tail;
+}
+
 static void irq_target_callback(struct fw_iso_context *context, u32 tstamp,
 				size_t header_length, void *header,
 				void *private_data)
 {
 	struct amdtp_stream *irq_target = private_data;
 	struct amdtp_domain *d = irq_target->domain;
+	unsigned int packets = header_length / sizeof(__be32);
 	struct amdtp_stream *s;
 
+	// Record enough entries with extra 3 cycles at least.
+	pool_ideal_seq_descs(d, packets + 3);
+
 	out_stream_callback(context, tstamp, header_length, header, irq_target);
 	if (amdtp_streaming_error(irq_target))
 		goto error;
@@ -1344,6 +1393,18 @@ static int get_current_cycle_time(struct fw_card *fw_card, int *cur_cycle)
  */
 int amdtp_domain_start(struct amdtp_domain *d, unsigned int ir_delay_cycle)
 {
+	static const struct {
+		unsigned int data_block;
+		unsigned int syt_offset;
+	} *entry, initial_state[] = {
+		[CIP_SFC_32000]  = {  4, 3072 },
+		[CIP_SFC_48000]  = {  6, 1024 },
+		[CIP_SFC_96000]  = { 12, 1024 },
+		[CIP_SFC_192000] = { 24, 1024 },
+		[CIP_SFC_44100]  = {  0,   67 },
+		[CIP_SFC_88200]  = {  0,   67 },
+		[CIP_SFC_176400] = {  0,   67 },
+	};
 	unsigned int events_per_buffer = d->events_per_buffer;
 	unsigned int events_per_period = d->events_per_period;
 	unsigned int idle_irq_interval;
@@ -1378,6 +1439,11 @@ int amdtp_domain_start(struct amdtp_domain *d, unsigned int ir_delay_cycle)
 	d->seq_size = queue_size;
 	d->seq_tail = 0;
 
+	entry = &initial_state[s->sfc];
+	d->data_block_state = entry->data_block;
+	d->syt_offset_state = entry->syt_offset;
+	d->last_syt_offset = TICKS_PER_CYCLE;
+
 	if (ir_delay_cycle > 0) {
 		struct fw_card *fw_card = fw_parent_device(s->unit)->card;
 
@@ -1414,6 +1480,7 @@ int amdtp_domain_start(struct amdtp_domain *d, unsigned int ir_delay_cycle)
 		} else {
 			// IT context starts immediately.
 			cycle_match = -1;
+			s->ctx_data.rx.seq_index = 0;
 		}
 
 		if (s != d->irq_target) {
@@ -1427,6 +1494,7 @@ int amdtp_domain_start(struct amdtp_domain *d, unsigned int ir_delay_cycle)
 	s = d->irq_target;
 	s->ctx_data.rx.events_per_period = events_per_period;
 	s->ctx_data.rx.event_count = 0;
+	s->ctx_data.rx.seq_index = 0;
 
 	idle_irq_interval = DIV_ROUND_UP(CYCLES_PER_SECOND * events_per_period,
 					 amdtp_rate_table[d->irq_target->sfc]);

sound/firewire/amdtp-stream.h

@@ -138,6 +138,8 @@ struct amdtp_stream {
 		struct {
 			// To calculate CIP data blocks and tstamp.
 			unsigned int transfer_delay;
+			unsigned int seq_index;
+
 			unsigned int data_block_state;
 			unsigned int last_syt_offset;
 			unsigned int syt_offset_state;
@@ -292,6 +294,10 @@ struct amdtp_domain {
 	struct seq_desc *seq_descs;
 	unsigned int seq_size;
 	unsigned int seq_tail;
+
+	unsigned int data_block_state;
+	unsigned int syt_offset_state;
+	unsigned int last_syt_offset;
 };
 
 int amdtp_domain_init(struct amdtp_domain *d);