@@ -665,6 +665,10 @@ static void handle_in_packet(struct amdtp_stream *s,
/* Check data block counter continuity */
data_block_counter = cip_header[0] & AMDTP_DBC_MASK;
+ if (data_blocks == 0 && (s->flags & CIP_EMPTY_HAS_WRONG_DBC) &&
+ s->data_block_counter != UINT_MAX)
+ data_block_counter = s->data_block_counter;
+
if (((s->flags & CIP_SKIP_DBC_ZERO_CHECK) && data_block_counter == 0) ||
(s->data_block_counter == UINT_MAX)) {
lost = false;
@@ -27,6 +27,8 @@
* skipped for detecting discontinuity.
* @CIP_SKIP_INIT_DBC_CHECK: Only for in-stream. The value of dbc in first
* packet is not continuous from an initial value.
+ * @CIP_EMPTY_HAS_WRONG_DBC: Only for in-stream. The value of dbc in empty
+ * packet is wrong but the others are correct.
*/
enum cip_flags {
CIP_NONBLOCKING = 0x00,
@@ -37,6 +39,7 @@ enum cip_flags {
CIP_WRONG_DBS = 0x10,
CIP_SKIP_DBC_ZERO_CHECK = 0x20,
CIP_SKIP_INIT_DBC_CHECK = 0x40,
+ CIP_EMPTY_HAS_WRONG_DBC = 0x80,
};
/**
@@ -457,6 +457,13 @@ int snd_bebob_stream_init_duplex(struct snd_bebob *bebob)
/* See comments in next function */
init_completion(&bebob->bus_reset);
bebob->tx_stream.flags |= CIP_SKIP_INIT_DBC_CHECK;
+ /*
+ * At high sampling rate, M-Audio special firmware transmits empty
+ * packet with the value of dbc incremented by 8 but the others are
+ * valid to IEC 61883-1.
+ */
+ if (bebob->maudio_special_quirk)
+ bebob->tx_stream.flags |= CIP_EMPTY_HAS_WRONG_DBC;
err = amdtp_stream_init(&bebob->rx_stream, bebob->unit,
AMDTP_OUT_STREAM, CIP_BLOCKING);
M-Audio Firewire 1814 has a quirk, ProjectMix I/O also has. They transmit empty packet with wrong value of dbc incremented by 8 at high sampling rate. According to IEC 61883-1, this value should be the same as the one in previous packet. This commit adds a flag named as CIP_EMPTY_HAS_WRONG_DBC. With flag, the value of dbc in empty packet is overwittern by an expected value. This is an example of this quirk: CIP Header 0 CIP Header 1 Payload size 010D0000 9004F759 210 010D0010 90040B59 210 010D0020 90042359 210 01020028 9004FFFF 2 <- 010D0030 90043759 210 010D0040 90044B59 210 010D0050 90046359 210 01020058 9004FFFF 2 <- 010D0060 90047759 210 010D0070 90048B59 210 010D0080 9004A359 210 01020088 9004FFFF 2 <- 010D0090 9004B759 210 010D00A0 9004CB59 210 010D00B0 9004E359 210 010200B8 9004FFFF 2 <- 010D00C0 9004F759 210 010D00D0 90040B59 210 010D00E0 90042359 210 Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> --- sound/firewire/amdtp.c | 4 ++++ sound/firewire/amdtp.h | 3 +++ sound/firewire/bebob/bebob_stream.c | 7 +++++++ 3 files changed, 14 insertions(+)