[alsa-devel] [PATCH 11/13] ALSA: dice: Support for non SYT-Match sampling clock source mode

[Takashi Sakamoto]

This commit allows another mode.

When sampling clock source is SYT-Match mode, devices handle
'presentation timestamp' in received packets and generates sampling clock
according to the information. In this case, driver is synchronization master
and must transfer correct value in SYT field of each packets in outgoing
stream, then the outgoing stream is a master stream.

On the other hand, non SYT-Match mode, devices do this. So drivers must pick
up the value in SYT field of incoming packets and use the value for outgoing
stream.

Signed-off-by: Takashi Sakamoto <o-takashi at sakamocchi.jp>
---
 sound/firewire/dice/dice-stream.c      | 33 +++++++++++++++++++++------------
 sound/firewire/dice/dice-transaction.c |  5 -----
 sound/firewire/dice/dice.h             |  2 --
 3 files changed, 21 insertions(+), 19 deletions(-)

diff --git a/sound/firewire/dice/dice-stream.c b/sound/firewire/dice/dice-stream.c
index d05178b..85ff927 100644
--- a/sound/firewire/dice/dice-stream.c
+++ b/sound/firewire/dice/dice-stream.c
@@ -163,9 +163,27 @@ end:
 
 static int get_sync_mode(struct snd_dice *dice, enum cip_flags *sync_mode)
 {
-	/* Currently, clock source is fixed at SYT-Match mode. */
-	*sync_mode = 0;
-	return 0;
+	u32 source;
+	int err;
+
+	err = snd_dice_transaction_get_clock_source(dice, &source);
+	if (err < 0)
+		goto end;
+
+	switch (source) {
+	/* So-called 'SYT Match' modes, sync_to_syt value of packets received */
+	case CLOCK_SOURCE_ARX4:	/* in 4th stream */
+	case CLOCK_SOURCE_ARX3:	/* in 3rd stream */
+	case CLOCK_SOURCE_ARX2:	/* in 2nd stream */
+		err = -ENOSYS;
+	case CLOCK_SOURCE_ARX1:	/* in 1st stream */
+		*sync_mode = 0;
+		break;
+	default:
+		*sync_mode = CIP_SYNC_TO_DEVICE;
+	}
+end:
+	return err;
 }
 
 int snd_dice_stream_start_duplex(struct snd_dice *dice, unsigned int rate)
@@ -322,15 +340,6 @@ int snd_dice_stream_init_duplex(struct snd_dice *dice)
 		goto end;
 
 	err = init_stream(dice, &dice->rx_stream);
-	if (err < 0)
-		goto end;
-
-	/* Currently, clock source is fixed at SYT-Match mode. */
-	err = snd_dice_transaction_set_clock_source(dice, CLOCK_SOURCE_ARX1);
-	if (err < 0) {
-		destroy_stream(dice, &dice->rx_stream);
-		destroy_stream(dice, &dice->tx_stream);
-	}
 end:
 	return err;
 }
diff --git a/sound/firewire/dice/dice-transaction.c b/sound/firewire/dice/dice-transaction.c
index 3e76219..25bb66b 100644
--- a/sound/firewire/dice/dice-transaction.c
+++ b/sound/firewire/dice/dice-transaction.c
@@ -131,11 +131,6 @@ int snd_dice_transaction_get_clock_source(struct snd_dice *dice,
 
 	return err;
 }
-int snd_dice_transaction_set_clock_source(struct snd_dice *dice,
-					  unsigned int source)
-{
-	return set_clock_info(dice, UINT_MAX, source);
-}
 
 int snd_dice_transaction_get_rate(struct snd_dice *dice, unsigned int *rate)
 {
diff --git a/sound/firewire/dice/dice.h b/sound/firewire/dice/dice.h
index a868485..8ea5cb4 100644
--- a/sound/firewire/dice/dice.h
+++ b/sound/firewire/dice/dice.h
@@ -152,8 +152,6 @@ static inline int snd_dice_transaction_read_sync(struct snd_dice *dice,
 					 buf, len);
 }
 
-int snd_dice_transaction_set_clock_source(struct snd_dice *dice,
-					  unsigned int source);
 int snd_dice_transaction_get_clock_source(struct snd_dice *dice,
 					  unsigned int *source);
 int snd_dice_transaction_set_rate(struct snd_dice *dice, unsigned int rate);
-- 
1.9.1