In kernel API of Linux FireWire subsystem, handlers of isochronous
receive (IR) context can get context headers as an argument of
callback. When 4 byte header is used, the context header includes
isochronous packet header for each packet. When 8 byte header is
used, it includes isochronous cycle as well.
ALSA IEC 61883-1/6 engine uses 4 byte header, and computes isochronous
cycle from the cycle of interrupt. The usage of 8 byte header can
obsolete the computation.
Furthermore, this change works well for a case that a series of
packet in one interrupt includes skipped isochronous cycle,
This commit uses 8 byte header to handle isochronous cycle.
Signed-off-by: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>
---
sound/firewire/amdtp-stream.c | 44 +++++++++++++++--------------------
1 file changed, 19 insertions(+), 25 deletions(-)
diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c
index 3ada55ed5381..43f28b813386 100644
--- a/sound/firewire/amdtp-stream.c
+++ b/sound/firewire/amdtp-stream.c
@@ -56,8 +56,9 @@
#define INTERRUPT_INTERVAL 16
#define QUEUE_LENGTH 48
-#define IN_PACKET_HEADER_SIZE 4
+#define IR_HEADER_SIZE 8 // For header and timestamp.
#define OUT_PACKET_HEADER_SIZE 0
+#define HEADER_TSTAMP_MASK 0x0000ffff
static void pcm_period_tasklet(unsigned long data);
@@ -456,7 +457,7 @@ static inline int queue_out_packet(struct amdtp_stream *s,
static inline int queue_in_packet(struct amdtp_stream *s)
{
- return queue_packet(s, IN_PACKET_HEADER_SIZE, s->max_payload_length);
+ return queue_packet(s, IR_HEADER_SIZE, s->max_payload_length);
}
static int handle_out_packet(struct amdtp_stream *s,
@@ -701,13 +702,6 @@ static inline u32 increment_cycle_count(u32 cycle, unsigned int addend)
return cycle;
}
-static inline u32 decrement_cycle_count(u32 cycle, unsigned int subtrahend)
-{
- if (cycle < subtrahend)
- cycle += 8 * CYCLES_PER_SECOND;
- return cycle - subtrahend;
-}
-
static void out_stream_callback(struct fw_iso_context *context, u32 tstamp,
size_t header_length, void *header,
void *private_data)
@@ -745,29 +739,26 @@ static void in_stream_callback(struct fw_iso_context *context, u32 tstamp,
struct amdtp_stream *s = private_data;
unsigned int i, packets;
unsigned int payload_length, max_payload_length;
- __be32 *headers = header;
- u32 cycle;
+ __be32 *ctx_header = header;
if (s->packet_index < 0)
return;
/* The number of packets in buffer */
- packets = header_length / IN_PACKET_HEADER_SIZE;
-
- cycle = compute_cycle_count(tstamp);
-
- /* Align to actual cycle count for the last packet. */
- cycle = decrement_cycle_count(cycle, packets);
+ packets = header_length / IR_HEADER_SIZE;
/* For buffer-over-run prevention. */
max_payload_length = s->max_payload_length;
for (i = 0; i < packets; i++) {
- cycle = increment_cycle_count(cycle, 1);
+ u32 iso_header = be32_to_cpu(ctx_header[0]);
+ unsigned int cycle;
+
+ tstamp = be32_to_cpu(ctx_header[1]) & HEADER_TSTAMP_MASK;
+ cycle = compute_cycle_count(tstamp);
/* The number of bytes in this packet */
- payload_length =
- (be32_to_cpu(headers[i]) >> ISO_DATA_LENGTH_SHIFT);
+ payload_length = iso_header >> ISO_DATA_LENGTH_SHIFT;
if (payload_length > max_payload_length) {
dev_err(&s->unit->device,
"Detect jumbo payload: %04x %04x\n",
@@ -777,6 +768,8 @@ static void in_stream_callback(struct fw_iso_context *context, u32 tstamp,
if (s->handle_packet(s, payload_length, cycle, i) < 0)
break;
+
+ ctx_header += IR_HEADER_SIZE / sizeof(__be32);
}
/* Queueing error or detecting invalid payload. */
@@ -797,6 +790,7 @@ static void amdtp_stream_first_callback(struct fw_iso_context *context,
void *header, void *private_data)
{
struct amdtp_stream *s = private_data;
+ __be32 *ctx_header = header;
u32 cycle;
unsigned int packets;
@@ -807,11 +801,10 @@ static void amdtp_stream_first_callback(struct fw_iso_context *context,
s->callbacked = true;
wake_up(&s->callback_wait);
- cycle = compute_cycle_count(tstamp);
-
if (s->direction == AMDTP_IN_STREAM) {
- packets = header_length / IN_PACKET_HEADER_SIZE;
- cycle = decrement_cycle_count(cycle, packets);
+ tstamp = be32_to_cpu(ctx_header[1]) & HEADER_TSTAMP_MASK;
+ cycle = compute_cycle_count(tstamp);
+
context->callback.sc = in_stream_callback;
if (s->flags & CIP_NO_HEADER)
s->handle_packet = handle_in_packet_without_header;
@@ -819,6 +812,7 @@ static void amdtp_stream_first_callback(struct fw_iso_context *context,
s->handle_packet = handle_in_packet;
} else {
packets = header_length / 4;
+ cycle = compute_cycle_count(tstamp);
cycle = increment_cycle_count(cycle, QUEUE_LENGTH - packets);
context->callback.sc = out_stream_callback;
if (s->flags & CIP_NO_HEADER)
@@ -880,7 +874,7 @@ int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed)
if (s->direction == AMDTP_IN_STREAM) {
dir = DMA_FROM_DEVICE;
type = FW_ISO_CONTEXT_RECEIVE;
- header_size = IN_PACKET_HEADER_SIZE;
+ header_size = IR_HEADER_SIZE;
} else {
dir = DMA_TO_DEVICE;
type = FW_ISO_CONTEXT_TRANSMIT;
--
2.19.1
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