diff options
Diffstat (limited to 'sound/firewire/amdtp-stream.c')
| -rw-r--r-- | sound/firewire/amdtp-stream.c | 42 |
1 files changed, 30 insertions, 12 deletions
diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c index 4484242da0e6..46f1167bf69f 100644 --- a/sound/firewire/amdtp-stream.c +++ b/sound/firewire/amdtp-stream.c @@ -548,26 +548,44 @@ end: return 0; } -static void out_stream_callback(struct fw_iso_context *context, u32 cycle, +/* + * In CYCLE_TIMER register of IEEE 1394, 7 bits are used to represent second. On + * the other hand, in DMA descriptors of 1394 OHCI, 3 bits are used to represent + * it. Thus, via Linux firewire subsystem, we can get the 3 bits for second. + */ +static inline u32 compute_cycle_count(u32 tstamp) +{ + return (((tstamp >> 13) & 0x07) * 8000) + (tstamp & 0x1fff); +} + +static inline u32 increment_cycle_count(u32 cycle, unsigned int addend) +{ + cycle += addend; + if (cycle >= 8 * CYCLES_PER_SECOND) + cycle -= 8 * CYCLES_PER_SECOND; + return cycle; +} + +static void out_stream_callback(struct fw_iso_context *context, u32 tstamp, size_t header_length, void *header, void *private_data) { struct amdtp_stream *s = private_data; unsigned int i, syt, packets = header_length / 4; unsigned int data_blocks; + u32 cycle; if (s->packet_index < 0) return; - /* - * Compute the cycle of the last queued packet. - * (We need only the four lowest bits for the SYT, so we can ignore - * that bits 0-11 must wrap around at 3072.) - */ - cycle += QUEUE_LENGTH - packets; + cycle = compute_cycle_count(tstamp); + + /* Align to actual cycle count for the last packet. */ + cycle = increment_cycle_count(cycle, QUEUE_LENGTH - packets); for (i = 0; i < packets; ++i) { - syt = calculate_syt(s, ++cycle); + cycle = increment_cycle_count(cycle, 1); + syt = calculate_syt(s, cycle); data_blocks = calculate_data_blocks(s, syt); if (handle_out_packet(s, data_blocks, syt) < 0) { @@ -580,7 +598,7 @@ static void out_stream_callback(struct fw_iso_context *context, u32 cycle, fw_iso_context_queue_flush(s->context); } -static void in_stream_callback(struct fw_iso_context *context, u32 cycle, +static void in_stream_callback(struct fw_iso_context *context, u32 tstamp, size_t header_length, void *header, void *private_data) { @@ -650,7 +668,7 @@ static void in_stream_callback(struct fw_iso_context *context, u32 cycle, } /* processing is done by master callback */ -static void slave_stream_callback(struct fw_iso_context *context, u32 cycle, +static void slave_stream_callback(struct fw_iso_context *context, u32 tstamp, size_t header_length, void *header, void *private_data) { @@ -659,7 +677,7 @@ static void slave_stream_callback(struct fw_iso_context *context, u32 cycle, /* this is executed one time */ static void amdtp_stream_first_callback(struct fw_iso_context *context, - u32 cycle, size_t header_length, + u32 tstamp, size_t header_length, void *header, void *private_data) { struct amdtp_stream *s = private_data; @@ -678,7 +696,7 @@ static void amdtp_stream_first_callback(struct fw_iso_context *context, else context->callback.sc = out_stream_callback; - context->callback.sc(context, cycle, header_length, header, s); + context->callback.sc(context, tstamp, header_length, header, s); } /** |