ALSA: bebob/firewire-lib: Add a quirk for discontinuity at bus reset

Normal BeBoB firmware has a quirk. When receiving bus reset, it transmits
packets with discontinuous value in dbc field.

This causes two situation, one is to abort streaming by firewire-lib as a
result of detecting the discontinuity. Another is to call driver's .update()
because of bus reset. These two is generated independently. (The former
depends on isochronous stream and the latter depends on IEEE1394 bus driver.)

When BeBoB driver works with XRUN-recoverable applications, this situation
looks like stream_start_duplex() call followed by stream_update_duplex() call
because applications will call snd_pcm_prepare() immediately at XRUN.

To update connections and streams at first, this commit use completion. When
queueing error occurs, stream_start_duplex() is forced to wait maximum
1000msec. During this, when .update() is called, the completion is waken and
stream_start_duplex() is processed without breaking connections.

At bus reset, stream_start_duplex() shouldn't break/establish connections and
stream_update_duplex() should update connections because a caller of
fw_iso_resources_allocate() is responsible for calling
fw_iso_resources_update() on bus reset.

This commit also adds a flag, which has an effect to skip checking continuity
for first packet. This flag is useful for BeBoB quirk to start handling packets
during streaming.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 7 insertions, 2 deletions

diff --git a/sound/firewire/amdtp.c b/sound/firewire/amdtp.c
index 28ee3d8..690c608 100644
--- a/sound/firewire/amdtp.c
+++ b/sound/firewire/amdtp.c
@@ -665,7 +665,8 @@ static void handle_in_packet(struct amdtp_stream *s,
 
 	/* Check data block counter continuity */
 	data_block_counter = cip_header[0] & AMDTP_DBC_MASK;
-	if ((s->flags & CIP_SKIP_DBC_ZERO_CHECK) && data_block_counter == 0) {
+	if (((s->flags & CIP_SKIP_DBC_ZERO_CHECK) && data_block_counter == 0) ||
+	    (s->data_block_counter == UINT_MAX)) {
 		lost = false;
 	} else if (!(s->flags & CIP_DBC_IS_END_EVENT)) {
 		lost = data_block_counter != s->data_block_counter;
@@ -850,7 +851,11 @@ int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed)
 		goto err_unlock;
 	}
 
-	s->data_block_counter = 0;
+	if (s->direction == AMDTP_IN_STREAM &&
+	    s->flags & CIP_SKIP_INIT_DBC_CHECK)
+		s->data_block_counter = UINT_MAX;
+	else
+		s->data_block_counter = 0;
 	s->data_block_state = initial_state[s->sfc].data_block;
 	s->syt_offset_state = initial_state[s->sfc].syt_offset;
 	s->last_syt_offset = TICKS_PER_CYCLE;