1 files changed, 26 insertions, 22 deletions

diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c
index 3aef6a78a188..b341bd86605e 100644
--- a/sound/firewire/amdtp-stream.c
+++ b/sound/firewire/amdtp-stream.c
@@ -519,13 +519,13 @@ static void build_it_pkt_header(struct amdtp_stream *s, unsigned int cycle,
 
 static int check_cip_header(struct amdtp_stream *s, const __be32 *buf,
 			    unsigned int payload_length,
-			    unsigned int *data_blocks, unsigned int *syt)
+			    unsigned int *data_blocks, unsigned int *dbc,
+			    unsigned int *syt)
 {
 	u32 cip_header[2];
 	unsigned int sph;
 	unsigned int fmt;
 	unsigned int fdf;
-	unsigned int data_block_counter;
 	bool lost;
 
 	cip_header[0] = be32_to_cpu(buf[0]);
@@ -577,17 +577,17 @@ static int check_cip_header(struct amdtp_stream *s, const __be32 *buf,
 	}
 
 	/* Check data block counter continuity */
-	data_block_counter = cip_header[0] & CIP_DBC_MASK;
+	*dbc = cip_header[0] & CIP_DBC_MASK;
 	if (*data_blocks == 0 && (s->flags & CIP_EMPTY_HAS_WRONG_DBC) &&
 	    s->data_block_counter != UINT_MAX)
-		data_block_counter = s->data_block_counter;
+		*dbc = s->data_block_counter;
 
 	if (((s->flags & CIP_SKIP_DBC_ZERO_CHECK) &&
-	     data_block_counter == s->ctx_data.tx.first_dbc) ||
+	     *dbc == s->ctx_data.tx.first_dbc) ||
 	    s->data_block_counter == UINT_MAX) {
 		lost = false;
 	} else if (!(s->flags & CIP_DBC_IS_END_EVENT)) {
-		lost = data_block_counter != s->data_block_counter;
+		lost = *dbc != s->data_block_counter;
 	} else {
 		unsigned int dbc_interval;
 
@@ -596,26 +596,18 @@ static int check_cip_header(struct amdtp_stream *s, const __be32 *buf,
 		else
 			dbc_interval = *data_blocks;
 
-		lost = data_block_counter !=
-		       ((s->data_block_counter + dbc_interval) & 0xff);
+		lost = *dbc != ((s->data_block_counter + dbc_interval) & 0xff);
 	}
 
 	if (lost) {
 		dev_err(&s->unit->device,
 			"Detect discontinuity of CIP: %02X %02X\n",
-			s->data_block_counter, data_block_counter);
+			s->data_block_counter, *dbc);
 		return -EIO;
 	}
 
 	*syt = cip_header[1] & CIP_SYT_MASK;
 
-	if (s->flags & CIP_DBC_IS_END_EVENT) {
-		s->data_block_counter = data_block_counter;
-	} else {
-		s->data_block_counter =
-				(data_block_counter + *data_blocks) & 0xff;
-	}
-
 	return 0;
 }
 
@@ -626,6 +618,7 @@ static int parse_ir_ctx_header(struct amdtp_stream *s, unsigned int cycle,
 			       unsigned int *syt, unsigned int index)
 {
 	const __be32 *cip_header;
+	unsigned int dbc;
 	int err;
 
 	*payload_length = be32_to_cpu(ctx_header[0]) >> ISO_DATA_LENGTH_SHIFT;
@@ -640,22 +633,33 @@ static int parse_ir_ctx_header(struct amdtp_stream *s, unsigned int cycle,
 	if (!(s->flags & CIP_NO_HEADER)) {
 		cip_header = ctx_header + 2;
 		err = check_cip_header(s, cip_header, *payload_length,
-				       data_blocks, syt);
-		if (err < 0)
-			return err;
+				       data_blocks, &dbc, syt);
+		if (err < 0) {
+			if (err != -EAGAIN)
+				return err;
+
+			*data_blocks = 0;
+			dbc = s->data_block_counter;
+		}
 	} else {
 		cip_header = NULL;
+		err = 0;
 		*data_blocks = *payload_length / sizeof(__be32) /
 			       s->data_block_quadlets;
+		dbc = s->data_block_counter;
 		*syt = 0;
-		s->data_block_counter =
-				(s->data_block_counter + *data_blocks) & 0xff;
 	}
 
+	if (err >= 0 && s->flags & CIP_DBC_IS_END_EVENT)
+		s->data_block_counter = dbc;
+
 	trace_amdtp_packet(s, cycle, cip_header, *payload_length, *data_blocks,
 			   index);
 
-	return 0;
+	if (err >= 0 && !(s->flags & CIP_DBC_IS_END_EVENT))
+		s->data_block_counter = (dbc + *data_blocks) & 0xff;
+
+	return err;
 }
 
 // In CYCLE_TIMER register of IEEE 1394, 7 bits are used to represent second. On