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ALSA: firewire-lib: fix wrong value for FDF field as an empty packet

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This commit fix out of specification about the value of FDF field in out packet
with 'no data'. This affects blocking mode.

According to IEC 61883-6, there is two way to generate AMDTP packets include no
data in blocking mode.

Way 1. an empty packet defined in IEC 61883-1
 - Size of packet is 2 quadlets.
 - The value of FDF is sfc.
 - The packet includes only CIP headers

Way 2. a special non-empty packet defined in IEC 61883-6
 - Size of packet is following to blocking mode
 - The value of FDF is 0xff. This value is 'NO-DATA'. This means 'The receiver'
   must ignore all the data in a CIP with this FDF code'.
 - The packet includes dummy data.

But current implementation is a combination of them.
 - Size of packet is 2 (way 1)
 - FDF = 0xff (way 2)
This causes BeBoB chipset cannot sound.

This patch applies Way 1.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Cc: Acked-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Sakamoto 2013-11-21 14:21:06 +09:00 committed by Takashi Iwai
parent 5db4d34b54
commit 82755abfe8
1 changed files with 6 additions and 9 deletions
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15
sound/firewire/amdtp.c
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@ -434,17 +434,14 @@ static void queue_out_packet(struct amdtp_out_stream *s, unsigned int cycle)
return;
index = s->packet_index;
/* this module generate empty packet for 'no data' */
syt = calculate_syt(s, cycle);
if (!(s->flags & CIP_BLOCKING)) {
if (!(s->flags & CIP_BLOCKING))
data_blocks = calculate_data_blocks(s);
} else {
if (syt != 0xffff) {
data_blocks = s->syt_interval;
} else {
data_blocks = 0;
syt = 0xffffff;
}
}
else if (syt != 0xffff)
data_blocks = s->syt_interval;
else
data_blocks = 0;
buffer = s->buffer.packets[index].buffer;
buffer[0] = cpu_to_be32(ACCESS_ONCE(s->source_node_id_field) |