diff options
Diffstat (limited to 'sound/firewire')
| -rw-r--r-- | sound/firewire/amdtp-stream.c | 83 |
1 files changed, 81 insertions, 2 deletions
diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c index 06a24a7f63c1..f7e1329efa0b 100644 --- a/sound/firewire/amdtp-stream.c +++ b/sound/firewire/amdtp-stream.c @@ -352,6 +352,9 @@ void amdtp_stream_pcm_prepare(struct amdtp_stream *s) } EXPORT_SYMBOL(amdtp_stream_pcm_prepare); +#define prev_packet_desc(s, desc) \ + list_prev_entry_circular(desc, &s->packet_descs_list, link) + static void pool_blocking_data_blocks(struct amdtp_stream *s, struct seq_desc *descs, unsigned int size, unsigned int pos, unsigned int count) { @@ -851,10 +854,15 @@ static int parse_ir_ctx_header(struct amdtp_stream *s, unsigned int 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_ohci_iso_ctx_cycle_count(u32 tstamp) +{ + return (((tstamp >> 13) & 0x07) * CYCLES_PER_SECOND) + (tstamp & 0x1fff); +} + static inline u32 compute_ohci_cycle_count(__be32 ctx_header_tstamp) { u32 tstamp = be32_to_cpu(ctx_header_tstamp) & HEADER_TSTAMP_MASK; - return (((tstamp >> 13) & 0x07) * 8000) + (tstamp & 0x1fff); + return compute_ohci_iso_ctx_cycle_count(tstamp); } static inline u32 increment_ohci_cycle_count(u32 cycle, unsigned int addend) @@ -865,6 +873,14 @@ static inline u32 increment_ohci_cycle_count(u32 cycle, unsigned int addend) return cycle; } +static inline u32 decrement_ohci_cycle_count(u32 minuend, u32 subtrahend) +{ + if (minuend < subtrahend) + minuend += OHCI_SECOND_MODULUS * CYCLES_PER_SECOND; + + return minuend - subtrahend; +} + static int compare_ohci_cycle_count(u32 lval, u32 rval) { if (lval == rval) @@ -1035,6 +1051,63 @@ static inline void cancel_stream(struct amdtp_stream *s) WRITE_ONCE(s->pcm_buffer_pointer, SNDRV_PCM_POS_XRUN); } +static snd_pcm_sframes_t compute_pcm_extra_delay(struct amdtp_stream *s, + const struct pkt_desc *desc, unsigned int count) +{ + unsigned int data_block_count = 0; + u32 latest_cycle; + u32 cycle_time; + u32 curr_cycle; + u32 cycle_gap; + int i, err; + + if (count == 0) + goto end; + + // Forward to the latest record. + for (i = 0; i < count - 1; ++i) + desc = amdtp_stream_next_packet_desc(s, desc); + latest_cycle = desc->cycle; + + err = fw_card_read_cycle_time(fw_parent_device(s->unit)->card, &cycle_time); + if (err < 0) + goto end; + + // Compute cycle count with lower 3 bits of second field and cycle field like timestamp + // format of 1394 OHCI isochronous context. + curr_cycle = compute_ohci_iso_ctx_cycle_count((cycle_time >> 12) & 0x0000ffff); + + if (s->direction == AMDTP_IN_STREAM) { + // NOTE: The AMDTP packet descriptor should be for the past isochronous cycle since + // it corresponds to arrived isochronous packet. + if (compare_ohci_cycle_count(latest_cycle, curr_cycle) > 0) + goto end; + cycle_gap = decrement_ohci_cycle_count(curr_cycle, latest_cycle); + + // NOTE: estimate delay by recent history of arrived AMDTP packets. The estimated + // value expectedly corresponds to a few packets (0-2) since the packet arrived at + // the most recent isochronous cycle has been already processed. + for (i = 0; i < cycle_gap; ++i) { + desc = amdtp_stream_next_packet_desc(s, desc); + data_block_count += desc->data_blocks; + } + } else { + // NOTE: The AMDTP packet descriptor should be for the future isochronous cycle + // since it was already scheduled. + if (compare_ohci_cycle_count(latest_cycle, curr_cycle) < 0) + goto end; + cycle_gap = decrement_ohci_cycle_count(latest_cycle, curr_cycle); + + // NOTE: use history of scheduled packets. + for (i = 0; i < cycle_gap; ++i) { + data_block_count += desc->data_blocks; + desc = prev_packet_desc(s, desc); + } + } +end: + return data_block_count * s->pcm_frame_multiplier; +} + static void process_ctx_payloads(struct amdtp_stream *s, const struct pkt_desc *desc, unsigned int count) @@ -1048,6 +1121,8 @@ static void process_ctx_payloads(struct amdtp_stream *s, if (pcm) { unsigned int data_block_count = 0; + pcm->runtime->delay = compute_pcm_extra_delay(s, desc, count); + for (i = 0; i < count; ++i) { data_block_count += desc->data_blocks; desc = amdtp_stream_next_packet_desc(s, desc); @@ -1686,7 +1761,11 @@ static int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed, else s->tag = TAG_CIP; - descs = kcalloc(s->queue_size, sizeof(*descs), GFP_KERNEL); + // NOTE: When operating without hardIRQ/softIRQ, applications tends to call ioctl request + // for runtime of PCM substream in the interval equivalent to the size of PCM buffer. It + // could take a round over queue of AMDTP packet descriptors and small loss of history. For + // safe, keep more 8 elements for the queue, equivalent to 1 ms. + descs = kcalloc(s->queue_size + 8, sizeof(*descs), GFP_KERNEL); if (!descs) { err = -ENOMEM; goto err_context; |