ALSA: firewire-lib: use 8 byte packet header for IT context to separate CIP header...

In Linux firewire subsystem, for IT context, some quadlets of isochronous
packet payload can be indicated as a part of packet header to queue to
the context.

This commit uses the packet header to split CIP headers from CIP
payload. As a result, regardless of CIP or non-CIP, context payload
includes data blocks only.

Signed-off-by: Takashi Sakamoto <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 e813d31..791efa5 100644 (file)
--- a/sound/firewire/amdtp-stream.c
+++ b/sound/firewire/amdtp-stream.c
@@ -62,6 +62,9 @@
 #define IR_CTX_HEADER_SIZE_NO_CIP      8
 #define HEADER_TSTAMP_MASK     0x0000ffff
 
+#define IT_PKT_HEADER_SIZE_CIP         8 // For 2 CIP header.
+#define IT_PKT_HEADER_SIZE_NO_CIP      0 // Nothing.
+
 static void pcm_period_tasklet(unsigned long data);
 
 /**
@@ -452,13 +455,10 @@ end:
 }
 
 static inline int queue_out_packet(struct amdtp_stream *s,
-                                  struct fw_iso_packet *params,
-                                  unsigned int payload_length)
+                                  struct fw_iso_packet *params)
 {
-       // No header for this packet.
-       params->header_length = 0;
-       params->payload_length = payload_length;
-       params->skip = !!(payload_length == 0);
+       params->skip =
+               !!(params->header_length == 0 && params->payload_length == 0);
        return queue_packet(s, params);
 }
 
@@ -491,41 +491,41 @@ static int handle_out_packet(struct amdtp_stream *s, unsigned int cycle,
 {
        unsigned int syt;
        unsigned int data_blocks;
-       unsigned int payload_length;
        __be32 *cip_header;
        unsigned int pcm_frames;
        struct snd_pcm_substream *pcm;
-       struct fw_iso_packet params = {0};
+       struct {
+               struct fw_iso_packet params;
+               __be32 header[IT_PKT_HEADER_SIZE_CIP / sizeof(__be32)];
+       } template = { {0}, {0} };
 
        syt = calculate_syt(s, cycle);
        data_blocks = calculate_data_blocks(s, syt);
-
-       payload_length = data_blocks * sizeof(__be32) * s->data_block_quadlets;
-       if (!(s->flags & CIP_NO_HEADER)) {
-               cip_header = buffer;
-               buffer += 2;
-               payload_length += 2 * sizeof(__be32);
-       } else {
-               cip_header = NULL;
-       }
-
        pcm_frames = s->process_data_blocks(s, buffer, data_blocks, &syt);
 
        if (s->flags & CIP_DBC_IS_END_EVENT)
                s->data_block_counter =
                                (s->data_block_counter + data_blocks) & 0xff;
 
-       if (cip_header)
+       if (!(s->flags & CIP_NO_HEADER)) {
+               cip_header = (__be32 *)template.params.header;
                generate_cip_header(s, cip_header, syt);
+               template.params.header_length = 2 * sizeof(__be32);
+       } else {
+               cip_header = NULL;
+       }
 
        if (!(s->flags & CIP_DBC_IS_END_EVENT))
                s->data_block_counter =
                                (s->data_block_counter + data_blocks) & 0xff;
 
-       trace_amdtp_packet(s, cycle, cip_header, payload_length, data_blocks,
-                          index);
+       template.params.payload_length =
+                       data_blocks * sizeof(__be32) * s->data_block_quadlets;
+
+       trace_amdtp_packet(s, cycle, cip_header, template.params.payload_length,
+                          data_blocks, index);
 
-       if (queue_out_packet(s, &params, payload_length) < 0)
+       if (queue_out_packet(s, &template.params) < 0)
                return -EIO;
 
        pcm = READ_ONCE(s->pcm);
@@ -878,14 +878,18 @@ int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed)
                        ctx_header_size = IR_CTX_HEADER_SIZE_CIP;
                else
                        ctx_header_size = IR_CTX_HEADER_SIZE_NO_CIP;
+
+               max_ctx_payload_size = amdtp_stream_get_max_payload(s) -
+                                      ctx_header_size;
        } else {
                dir = DMA_TO_DEVICE;
                type = FW_ISO_CONTEXT_TRANSMIT;
                ctx_header_size = 0;    // No effect for IT context.
-       }
 
-       max_ctx_payload_size = amdtp_stream_get_max_payload(s) -
-                              ctx_header_size;
+               max_ctx_payload_size = amdtp_stream_get_max_payload(s);
+               if (!(s->flags & CIP_NO_HEADER))
+                       max_ctx_payload_size -= IT_PKT_HEADER_SIZE_CIP;
+       }
 
        err = iso_packets_buffer_init(&s->buffer, s->unit, QUEUE_LENGTH,
                                      max_ctx_payload_size, dir);
@@ -918,10 +922,13 @@ int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed)
        s->packet_index = 0;
        do {
                struct fw_iso_packet params;
-               if (s->direction == AMDTP_IN_STREAM)
+               if (s->direction == AMDTP_IN_STREAM) {
                        err = queue_in_packet(s, &params);
-               else
-                       err = queue_out_packet(s, &params, 0);
+               } else {
+                       params.header_length = 0;
+                       params.payload_length = 0;
+                       err = queue_out_packet(s, &params);
+               }
                if (err < 0)
                        goto err_context;
        } while (s->packet_index > 0);