Commit 9d59124c authored by Takashi Sakamoto's avatar Takashi Sakamoto Committed by Takashi Iwai
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ALSA: bebob/firewire-lib: Add a quirk of wrong dbc in empty packet for M-Audio... 


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: default avatarTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 3149ac48

sound/firewire/amdtp.c

+4 −0
Original line number Diff line number Diff line
@@ -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;

sound/firewire/amdtp.h

+3 −0
Original line number Diff line number Diff line
@@ -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,

};



/**

sound/firewire/bebob/bebob_stream.c

+7 −0
Original line number Diff line number Diff line
@@ -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);

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