[alsa-devel] [PATCH 09/11] ALSA: bebob: loosen up severity of checking continuity for BeBoB v3 quirk

[Takashi Sakamoto]

PrismSound Orpheus, Behringer UFX1604 and FCA610 work with BeBoB v3 and
they're confirmed to transmit discontinuous packets in the beginning of
streaming.

payload    CIP headers
  8        0x00070000 0x9002FFFF
  8        0x00070000 0x9002FFFF
  8        0x00070000 0x9002FFFF
  8        0x00070008 0x9002FFFF <-
  8        0x00070008 0x9002FFFF
  8        0x00070008 0x9002FFFF
  8        0x00070008 0x9002FFFF
  8        0x00070008 0x9002FFFF
  8        0x00070008 0x9002FFFF
232        0x00070000 0x9002E798 <-
232        0x00070008 0x9002FB99
232        0x00070010 0x90021398
  8        0x00070018 0x9002FFFF
(This sample was got with Behringer FCA610 and FFADO library.)

This commit sets CIP_EMPTY_HAS_WRONG_DBC and CIP_SKIP_DBC_ZERO_CHECK to
ignore these discontinuities.

Tested-by: Kim Tore Jensen <kim at incendio.no>
Signed-off-by: Takashi Sakamoto <o-takashi at sakamocchi.jp>
---
 sound/firewire/bebob/bebob_stream.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/sound/firewire/bebob/bebob_stream.c b/sound/firewire/bebob/bebob_stream.c
index 9c810f9..d0df6c1 100644
--- a/sound/firewire/bebob/bebob_stream.c
+++ b/sound/firewire/bebob/bebob_stream.c
@@ -540,6 +540,17 @@ 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;
+
+	/*
+	 * BeBoB v3 transfers packets with these qurks:
+	 *  - In the beginning of streaming, the value of dbc is incremented
+	 *    even if no data blocks are transferred.
+	 *  - The value of dbc is reset suddenly.
+	 */
+	if (bebob->version > 2)
+		bebob->tx_stream.flags |= CIP_EMPTY_HAS_WRONG_DBC |
+					  CIP_SKIP_DBC_ZERO_CHECK;
+
 	/*
 	 * At high sampling rate, M-Audio special firmware transmits empty
 	 * packet with the value of dbc incremented by 8 but the others are
-- 
2.1.4