ALSA: firewire-motu: sequence replay for source packet header

This commit takes ALSA firewire-motu driver to perform sequence replay for
media clock recovery.

Unlike the other types of device, the devices in MOTU FireWire series
require two levels of sequence replay; the sequence of the number of
data blocks per packet and the sequence of source packet header per data
block. The former is already cached by ALSA IEC 61883-1/6 packet streaming
engine and ready to be replayed. The latter is also cached by ALSA
firewire-motu driver itself with a previous patch. This commit takes
the driver to replay both of them from the caches.

The sequence replay is tested with below models:

 * 828 mkII
 * Traveler
 * UltraLite
 * 828 mk3 FireWire
 * 828 mk3 Hybrid (except for high sampling transfer frequency
 * UltraLite mk3 FireWire
 * 4pre
 * AudioExpress

Unfortunately, below models still don't generate better sound, requires
more work:

 * 8pre
 * 828 mk3 Hybrid at high sampling transfer frequency

As long as I know, MOTU protocol version 1 requires extra care of the
format of data block, thus below models are not supported yet in this
time:

 * 828
 * 896

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20210602013406.26442-4-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/firewire/motu/amdtp-motu.c b/sound/firewire/motu/amdtp-motu.c
index 1741ceb..5388b85 100644 (file)
--- a/sound/firewire/motu/amdtp-motu.c
+++ b/sound/firewire/motu/amdtp-motu.c
@@ -20,10 +20,6 @@
 #define CYCLES_PER_SECOND      8000
 #define TICKS_PER_SECOND       (TICKS_PER_CYCLE * CYCLES_PER_SECOND)
 
-#define IEEE1394_SEC_MODULUS   128
-
-#define TRANSFER_DELAY_TICKS   0x2e00 /* 479.17 microseconds */
-
 #define CIP_SPH_CYCLE_SHIFT    12
 #define CIP_SPH_CYCLE_MASK     0x01fff000
 #define CIP_SPH_OFFSET_MASK    0x00000fff
@@ -35,14 +31,6 @@
 #define MIDI_BYTES_PER_SECOND  3093
 
 struct amdtp_motu {
-       /* For timestamp processing.  */
-       unsigned int quotient_ticks_per_event;
-       unsigned int remainder_ticks_per_event;
-       unsigned int next_ticks;
-       unsigned int next_accumulated;
-       unsigned int next_cycles;
-       unsigned int next_seconds;
-
        unsigned int pcm_chunks;
        unsigned int pcm_byte_offset;
 
@@ -61,20 +49,8 @@ int amdtp_motu_set_parameters(struct amdtp_stream *s, unsigned int rate,
                              unsigned int midi_ports,
                              struct snd_motu_packet_format *formats)
 {
-       static const struct {
-               unsigned int quotient_ticks_per_event;
-               unsigned int remainder_ticks_per_event;
-       } params[] = {
-               [CIP_SFC_44100]  = { 557, 123 },
-               [CIP_SFC_48000]  = { 512,   0 },
-               [CIP_SFC_88200]  = { 278, 282 },
-               [CIP_SFC_96000]  = { 256,   0 },
-               [CIP_SFC_176400] = { 139, 141 },
-               [CIP_SFC_192000] = { 128,   0 },
-       };
        struct amdtp_motu *p = s->protocol;
        unsigned int pcm_chunks, data_chunks, data_block_quadlets;
-       unsigned int delay;
        unsigned int mode;
        int i, err;
 
@@ -111,18 +87,6 @@ int amdtp_motu_set_parameters(struct amdtp_stream *s, unsigned int rate,
        p->midi_db_count = 0;
        p->midi_db_interval = rate / MIDI_BYTES_PER_SECOND;
 
-       delay = TRANSFER_DELAY_TICKS;
-
-       // For no-data or empty packets to adjust PCM sampling frequency.
-       delay += TICKS_PER_SECOND * s->syt_interval / rate;
-
-       p->next_seconds = 0;
-       p->next_cycles = delay / TICKS_PER_CYCLE;
-       p->quotient_ticks_per_event = params[s->sfc].quotient_ticks_per_event;
-       p->remainder_ticks_per_event = params[s->sfc].remainder_ticks_per_event;
-       p->next_ticks = delay % TICKS_PER_CYCLE;
-       p->next_accumulated = 0;
-
        return 0;
 }
 
@@ -400,47 +364,26 @@ static unsigned int process_ir_ctx_payloads(struct amdtp_stream *s,
        return pcm_frames;
 }
 
-static inline void compute_next_elapse_from_start(struct amdtp_motu *p)
+static void write_sph(struct amdtp_motu_cache *cache, __be32 *buffer, unsigned int data_blocks,
+                     unsigned int data_block_quadlets)
 {
-       p->next_accumulated += p->remainder_ticks_per_event;
-       if (p->next_accumulated >= 441) {
-               p->next_accumulated -= 441;
-               p->next_ticks++;
-       }
-
-       p->next_ticks += p->quotient_ticks_per_event;
-       if (p->next_ticks >= TICKS_PER_CYCLE) {
-               p->next_ticks -= TICKS_PER_CYCLE;
-               p->next_cycles++;
-       }
-
-       if (p->next_cycles >= CYCLES_PER_SECOND) {
-               p->next_cycles -= CYCLES_PER_SECOND;
-               p->next_seconds++;
-       }
-
-       if (p->next_seconds >= IEEE1394_SEC_MODULUS)
-               p->next_seconds -= IEEE1394_SEC_MODULUS;
-}
-
-static void write_sph(struct amdtp_stream *s, __be32 *buffer, unsigned int data_blocks,
-                     const unsigned int rx_start_cycle)
-{
-       struct amdtp_motu *p = s->protocol;
-       unsigned int next_cycles;
-       unsigned int i;
-       u32 sph;
+       unsigned int *event_offsets = cache->event_offsets;
+       const unsigned int cache_size = cache->size;
+       unsigned int cache_head = cache->head;
+       unsigned int base_tick = cache->rx_cycle_count * TICKS_PER_CYCLE;
+       int i;
 
        for (i = 0; i < data_blocks; i++) {
-               next_cycles = (rx_start_cycle + p->next_cycles) % CYCLES_PER_SECOND;
-               sph = ((next_cycles << CIP_SPH_CYCLE_SHIFT) | p->next_ticks) &
-                     (CIP_SPH_CYCLE_MASK | CIP_SPH_OFFSET_MASK);
+               unsigned int tick = (base_tick + event_offsets[cache_head]) % TICKS_PER_SECOND;
+               u32 sph = ((tick / TICKS_PER_CYCLE) << CIP_SPH_CYCLE_SHIFT) | (tick % TICKS_PER_CYCLE);
                *buffer = cpu_to_be32(sph);
 
-               compute_next_elapse_from_start(p);
-
-               buffer += s->data_block_quadlets;
+               cache_head = (cache_head + 1) % cache_size;
+               buffer += data_block_quadlets;
        }
+
+       cache->head = cache_head;
+       cache->rx_cycle_count = (cache->rx_cycle_count + 1) % CYCLES_PER_SECOND;
 }
 
 static unsigned int process_it_ctx_payloads(struct amdtp_stream *s,
@@ -448,11 +391,13 @@ static unsigned int process_it_ctx_payloads(struct amdtp_stream *s,
                                            unsigned int packets,
                                            struct snd_pcm_substream *pcm)
 {
-       const unsigned int rx_start_cycle = s->domain->processing_cycle.rx_start;
        struct amdtp_motu *p = s->protocol;
        unsigned int pcm_frames = 0;
        int i;
 
+       if (p->cache->rx_cycle_count == UINT_MAX)
+               p->cache->rx_cycle_count = (s->domain->processing_cycle.rx_start % CYCLES_PER_SECOND);
+
        // For data block processing.
        for (i = 0; i < packets; ++i) {
                const struct pkt_desc *desc = descs + i;
@@ -471,7 +416,7 @@ static unsigned int process_it_ctx_payloads(struct amdtp_stream *s,
 
                // TODO: how to interact control messages between userspace?
 
-               write_sph(s, buf, data_blocks, rx_start_cycle);
+               write_sph(p->cache, buf, data_blocks, s->data_block_quadlets);
        }
 
        // For tracepoints.

diff --git a/sound/firewire/motu/motu-stream.c b/sound/firewire/motu/motu-stream.c
index 3690025..43ff5be 100644 (file)
--- a/sound/firewire/motu/motu-stream.c
+++ b/sound/firewire/motu/motu-stream.c
@@ -274,8 +274,13 @@ int snd_motu_stream_start_duplex(struct snd_motu *motu)
 
                motu->cache.tail = 0;
                motu->cache.tx_cycle_count = UINT_MAX;
+               motu->cache.head = 0;
+               motu->cache.rx_cycle_count = UINT_MAX;
 
-               err = amdtp_domain_start(&motu->domain, 0, false, false);
+               // NOTE: The device requires both of replay; the sequence of the number of data
+               // blocks per packet, and the sequence of source packet header per data block as
+               // presentation time.
+               err = amdtp_domain_start(&motu->domain, 0, true, false);
                if (err < 0)
                        goto stop_streams;
 

diff --git a/sound/firewire/motu/motu.h b/sound/firewire/motu/motu.h
index 10ba870..674e3dc 100644 (file)
--- a/sound/firewire/motu/motu.h
+++ b/sound/firewire/motu/motu.h
@@ -44,6 +44,8 @@ struct amdtp_motu_cache {
        unsigned int size;
        unsigned int tail;
        unsigned int tx_cycle_count;
+       unsigned int head;
+       unsigned int rx_cycle_count;
 };
 
 struct snd_motu {