ALSA: firewire-lib: insert descriptor for skipped cycle

This commit fulfils sequence descriptors for skipped cycle when
it's one cycle. This is preparation for future integration.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20210518130048.146596-9-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c
index 78b62a4..af5c362 100644 (file)
--- a/sound/firewire/amdtp-stream.c
+++ b/sound/firewire/amdtp-stream.c
@@ -723,7 +723,8 @@ static inline u32 compute_ohci_it_cycle(const __be32 ctx_header_tstamp,
 static int generate_device_pkt_descs(struct amdtp_stream *s,
                                     struct pkt_desc *descs,
                                     const __be32 *ctx_header,
-                                    unsigned int packets)
+                                    unsigned int packets,
+                                    unsigned int *desc_count)
 {
        unsigned int next_cycle = s->next_cycle;
        unsigned int dbc = s->data_block_counter;
@@ -732,8 +733,9 @@ static int generate_device_pkt_descs(struct amdtp_stream *s,
        int i;
        int err;
 
+       *desc_count = 0;
        for (i = 0; i < packets; ++i) {
-               struct pkt_desc *desc = descs + i;
+               struct pkt_desc *desc = descs + *desc_count;
                unsigned int cycle;
                bool lost;
                unsigned int data_blocks;
@@ -745,11 +747,25 @@ static int generate_device_pkt_descs(struct amdtp_stream *s,
                        if (s->flags & CIP_NO_HEADER) {
                                // Fireface skips transmission just for an isoc cycle corresponding
                                // to empty packet.
+                               unsigned int prev_cycle = next_cycle;
+
                                next_cycle = increment_ohci_cycle_count(next_cycle, 1);
                                lost = (next_cycle != cycle);
+                               if (!lost) {
+                                       // Prepare a description for the skipped cycle for
+                                       // sequence replay.
+                                       desc->cycle = prev_cycle;
+                                       desc->syt = 0;
+                                       desc->data_blocks = 0;
+                                       desc->data_block_counter = dbc;
+                                       desc->ctx_payload = NULL;
+                                       ++desc;
+                                       ++(*desc_count);
+                               }
                        } else if (s->flags & CIP_JUMBO_PAYLOAD) {
                                // OXFW970 skips transmission for several isoc cycles during
-                               // asynchronous transaction.
+                               // asynchronous transaction. The sequence replay is impossible due
+                               // to the reason.
                                unsigned int safe_cycle = increment_ohci_cycle_count(next_cycle,
                                                                IR_JUMBO_PAYLOAD_MAX_SKIP_CYCLES);
                                lost = (compare_ohci_cycle_count(safe_cycle, cycle) > 0);
@@ -776,6 +792,7 @@ static int generate_device_pkt_descs(struct amdtp_stream *s,
                        dbc = (dbc + desc->data_blocks) & 0xff;
 
                next_cycle = increment_ohci_cycle_count(next_cycle, 1);
+               ++(*desc_count);
                ctx_header += s->ctx_data.tx.ctx_header_size / sizeof(*ctx_header);
                packet_index = (packet_index + 1) % queue_size;
        }
@@ -927,6 +944,7 @@ static void in_stream_callback(struct fw_iso_context *context, u32 tstamp,
        struct amdtp_stream *s = private_data;
        __be32 *ctx_header = header;
        unsigned int packets;
+       unsigned int desc_count;
        int i;
        int err;
 
@@ -936,14 +954,15 @@ static void in_stream_callback(struct fw_iso_context *context, u32 tstamp,
        // Calculate the number of packets in buffer and check XRUN.
        packets = header_length / s->ctx_data.tx.ctx_header_size;
 
-       err = generate_device_pkt_descs(s, s->pkt_descs, ctx_header, packets);
+       desc_count = 0;
+       err = generate_device_pkt_descs(s, s->pkt_descs, ctx_header, packets, &desc_count);
        if (err < 0) {
                if (err != -EAGAIN) {
                        cancel_stream(s);
                        return;
                }
        } else {
-               process_ctx_payloads(s, s->pkt_descs, packets);
+               process_ctx_payloads(s, s->pkt_descs, desc_count);
        }
 
        for (i = 0; i < packets; ++i) {