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ALSA: bebob/firewire-lib: Add a quirk of wrong dbc in empty packet for M-Audio special Firewire series

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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>
This commit is contained in:
Takashi Sakamoto 2014-04-25 22:45:27 +09:00 committed by Takashi Iwai
parent 3149ac489f
commit 9d59124cac
3 changed files with 14 additions and 0 deletions
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4
sound/firewire/amdtp.c
View File

@ -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;

3
sound/firewire/amdtp.h
View File

@ -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,
};
/**

7
sound/firewire/bebob/bebob_stream.c
View File

@ -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);