[alsa-devel] [PATCH] [05/29] ALSA: dice, firewire-lib: add blocking mode

[Clemens Ladisch]

Allow AMDTP output streams to use blocking mode.

Use it for DICE devices, because the old DICE-II chip will in some cases
not be able to lock to non-blocking streams (erratum E7).

Signed-off-by: Clemens Ladisch <clemens at ladisch.de>
---
 sound/firewire/amdtp.c |   54 ++++++++++++++++++++++++++----------------------
 sound/firewire/amdtp.h |    7 +++++-
 sound/firewire/dice.c  |    2 +-
 3 files changed, 36 insertions(+), 27 deletions(-)

diff --git a/sound/firewire/amdtp.c b/sound/firewire/amdtp.c
index ea995af..efb2e29 100644
--- a/sound/firewire/amdtp.c
+++ b/sound/firewire/amdtp.c
@@ -42,9 +42,6 @@ static void pcm_period_tasklet(unsigned long data);
 int amdtp_out_stream_init(struct amdtp_out_stream *s, struct fw_unit *unit,
 			  enum cip_out_flags flags)
 {
-	if (flags != CIP_NONBLOCKING)
-		return -EINVAL;
-
 	s->unit = fw_unit_get(unit);
 	s->flags = flags;
 	s->context = ERR_PTR(-1);
@@ -96,12 +93,20 @@ void amdtp_out_stream_set_rate(struct amdtp_out_stream *s, unsigned int rate)
 		return;

 	for (sfc = 0; sfc < ARRAY_SIZE(rate_info); ++sfc)
-		if (rate_info[sfc].rate == rate) {
-			s->sfc = sfc;
-			s->syt_interval = rate_info[sfc].syt_interval;
-			return;
-		}
+		if (rate_info[sfc].rate == rate)
+			goto sfc_found;
 	WARN_ON(1);
+	return;
+
+sfc_found:
+	s->sfc = sfc;
+	s->syt_interval = rate_info[sfc].syt_interval;
+
+	/* default buffering in the device */
+	s->transfer_delay = TRANSFER_DELAY_TICKS - TICKS_PER_CYCLE;
+	if (s->flags & CIP_BLOCKING)
+		/* additional buffering needed to adjust for no-data packets */
+		s->transfer_delay += TICKS_PER_SECOND * s->syt_interval / rate;
 }
 EXPORT_SYMBOL(amdtp_out_stream_set_rate);

@@ -110,25 +115,15 @@ EXPORT_SYMBOL(amdtp_out_stream_set_rate);
  * @s: the AMDTP output stream
  *
  * This function must not be called before the stream has been configured
- * with amdtp_out_stream_set_hw_params(), amdtp_out_stream_set_pcm(), and
+ * with amdtp_out_stream_set_rate(), amdtp_out_stream_set_pcm(), and
  * amdtp_out_stream_set_midi().
  */
 unsigned int amdtp_out_stream_get_max_payload(struct amdtp_out_stream *s)
 {
-	static const unsigned int max_data_blocks[] = {
-		[CIP_SFC_32000]  =  4,
-		[CIP_SFC_44100]  =  6,
-		[CIP_SFC_48000]  =  6,
-		[CIP_SFC_88200]  = 12,
-		[CIP_SFC_96000]  = 12,
-		[CIP_SFC_176400] = 23,
-		[CIP_SFC_192000] = 24,
-	};
-
 	s->data_block_quadlets = s->pcm_channels;
 	s->data_block_quadlets += DIV_ROUND_UP(s->midi_ports, 8);

-	return 8 + max_data_blocks[s->sfc] * 4 * s->data_block_quadlets;
+	return 8 + s->syt_interval * s->data_block_quadlets * 4;
 }
 EXPORT_SYMBOL(amdtp_out_stream_get_max_payload);

@@ -248,7 +243,7 @@ static unsigned int calculate_syt(struct amdtp_out_stream *s,
 	s->last_syt_offset = syt_offset;

 	if (syt_offset < TICKS_PER_CYCLE) {
-		syt_offset += TRANSFER_DELAY_TICKS - TICKS_PER_CYCLE;
+		syt_offset += s->transfer_delay;
 		syt = (cycle + syt_offset / TICKS_PER_CYCLE) << 12;
 		syt += syt_offset % TICKS_PER_CYCLE;

@@ -344,8 +339,17 @@ static void queue_out_packet(struct amdtp_out_stream *s, unsigned int cycle)
 		return;
 	index = s->packet_index;

-	data_blocks = calculate_data_blocks(s);
 	syt = calculate_syt(s, cycle);
+	if (!(s->flags & CIP_BLOCKING)) {
+		data_blocks = calculate_data_blocks(s);
+	} else {
+		if (syt != 0xffff) {
+			data_blocks = s->syt_interval;
+		} else {
+			data_blocks = 0;
+			syt = 0xffffff;
+		}
+	}

 	buffer = s->buffer.packets[index].buffer;
 	buffer[0] = cpu_to_be32(ACCESS_ONCE(s->source_node_id_field) |
@@ -455,9 +459,9 @@ static int queue_initial_skip_packets(struct amdtp_out_stream *s)
  * @speed: firewire speed code
  *
  * The stream cannot be started until it has been configured with
- * amdtp_out_stream_set_hw_params(), amdtp_out_stream_set_pcm(), and
- * amdtp_out_stream_set_midi(); and it must be started before any
- * PCM or MIDI device can be started.
+ * amdtp_out_stream_set_rate(), amdtp_out_stream_set_pcm(),
+ * amdtp_out_stream_set_midi(), and amdtp_out_stream_set_format();
+ * and it must be started before any PCM or MIDI device can be started.
  */
 int amdtp_out_stream_start(struct amdtp_out_stream *s, int channel, int speed)
 {
diff --git a/sound/firewire/amdtp.h b/sound/firewire/amdtp.h
index f6103d6..fd4ce30 100644
--- a/sound/firewire/amdtp.h
+++ b/sound/firewire/amdtp.h
@@ -11,9 +11,13 @@
  *	sample_rate/8000 samples, with rounding up or down to adjust
  *	for clock skew and left-over fractional samples.  This should
  *	be used if supported by the device.
+ * @CIP_BLOCKING: In blocking mode, each packet contains either zero or
+ *	SYT_INTERVAL samples, with these two types alternating so that
+ *	the overall sample rate comes out right.
  */
 enum cip_out_flags {
-	CIP_NONBLOCKING = 0,
+	CIP_NONBLOCKING	= 0x00,
+	CIP_BLOCKING	= 0x01,
 };

 /**
@@ -51,6 +55,7 @@ struct amdtp_out_stream {
 				 __be32 *buffer, unsigned int frames);

 	unsigned int syt_interval;
+	unsigned int transfer_delay;
 	unsigned int source_node_id_field;
 	struct iso_packets_buffer buffer;

diff --git a/sound/firewire/dice.c b/sound/firewire/dice.c
index 02c7b5a..63446f8 100644
--- a/sound/firewire/dice.c
+++ b/sound/firewire/dice.c
@@ -942,7 +942,7 @@ static int dice_probe(struct fw_unit *unit, const struct ieee1394_device_id *id)
 		goto err_notification_handler;
 	dice->resources.channels_mask = 0x00000000ffffffffuLL;

-	err = amdtp_out_stream_init(&dice->stream, unit, CIP_NONBLOCKING);
+	err = amdtp_out_stream_init(&dice->stream, unit, CIP_BLOCKING);
 	if (err < 0)
 		goto err_resources;