ALSA: firewire-lib: add syt_override member for some protocols

Some protocols don't use syt field of CIP header to represent
presentation timestamp. For such protocol, ALSA IEC 61883-1/6
packet streaming engine uses a pointer into local variable for
the value of syt to call data block processing layer. However,
it can decide the value when initializing packet streaming
layer.

This commit adds 'syt_override' member for packet streaming
layer.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/amdtp-stream.c

@@ -104,6 +104,9 @@ int amdtp_stream_init(struct amdtp_stream *s, struct fw_unit *unit,
 	s->fmt = fmt;
 	s->process_data_blocks = process_data_blocks;
 
+	if (dir == AMDTP_OUT_STREAM)
+		s->ctx_data.rx.syt_override = -1;
+
 	return 0;
 }
 EXPORT_SYMBOL(amdtp_stream_init);
@@ -717,6 +720,9 @@ static void out_stream_callback(struct fw_iso_context *context, u32 tstamp,
 		if (s->flags & CIP_DBC_IS_END_EVENT)
 			dbc = (dbc + data_blocks) & 0xff;
 
+		if (s->ctx_data.rx.syt_override >= 0)
+			syt = s->ctx_data.rx.syt_override;
+
 		build_it_pkt_header(s, cycle, &template.params, data_blocks,
 				    dbc, syt, i);
 

sound/firewire/amdtp-stream.h

@@ -133,6 +133,7 @@ struct amdtp_stream {
 
 			// To generate CIP header.
 			unsigned int fdf;
+			int syt_override;
 		} rx;
 	} ctx_data;
 

sound/firewire/motu/amdtp-motu.c

@@ -428,7 +428,13 @@ int amdtp_motu_init(struct amdtp_stream *s, struct fw_unit *unit,
 		return err;
 
 	s->sph = 1;
+
+	if (dir == AMDTP_OUT_STREAM) {
+		// Use fixed value for FDF field.
 		s->ctx_data.rx.fdf = MOTU_FDF_AM824;
+		// Not used.
+		s->ctx_data.rx.syt_override = 0xffff;
+	}
 
 	return 0;
 }

sound/firewire/tascam/amdtp-tascam.c

@@ -220,8 +220,12 @@ int amdtp_tscm_init(struct amdtp_stream *s, struct fw_unit *unit,
 	if (err < 0)
 		return 0;
 
-	/* Use fixed value for FDF field. */
+	if (dir == AMDTP_OUT_STREAM) {
+		// Use fixed value for FDF field.
 		s->ctx_data.rx.fdf = 0x00;
+		// Not used.
+		s->ctx_data.rx.syt_override = 0x0000;
+	}
 
 	/* This protocol uses fixed number of data channels for PCM samples. */
 	p = s->protocol;