From 9d59124cacf5d0a1e89aee83de6233bdf97afdb1 Mon Sep 17 00:00:00 2001 From: Takashi Sakamoto Date: Fri, 25 Apr 2014 22:45:27 +0900 Subject: 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 Signed-off-by: Takashi Iwai --- sound/firewire/bebob/bebob_stream.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'sound/firewire/bebob') diff --git a/sound/firewire/bebob/bebob_stream.c b/sound/firewire/bebob/bebob_stream.c index 2695b7899410..3e74d9b1e357 100644 --- a/sound/firewire/bebob/bebob_stream.c +++ b/sound/firewire/bebob/bebob_stream.c @@ -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); -- cgit v1.2.3