ALSA: bebob/firewire-lib: Add a quirk of wrong dbc in empty packet for M-Audio special Firewire series
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>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/firewire/bebob/bebob_stream.c b/sound/firewire/bebob/bebob_stream.c
index 2695b78..3e74d9b 100644
--- a/sound/firewire/bebob/bebob_stream.c
+++ b/sound/firewire/bebob/bebob_stream.c
@@ -457,6 +457,13 @@
/* 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);