Thanks for the update. This bit me last night, and I just commented out the check to keep working.

I'll try and retest it tonight with this version. (On a Echo Audiofire Pre8 with firmware  < 5)

Regards,

Euan deKock.

On 23 March 2014 10:16:58 AM AWST, Takashi Sakamoto <o-takashi@sakamocchi.jp> wrote:
>I realize this patch includes a bug to cause wrong detection of packet 
>discontinuity.
>
>> @@ -745,6 +745,8 @@ static void handle_in_packet(struct amdtp_stream
>*s,
>>
>>   	/* Check data block counter continuity */
>>   	data_block_counter = cip_header[0] & AMDTP_DBC_MASK;
>> +	if (data_blocks == 0 && (s->flags & CIP_EMPTY_HAS_WRONG_DBC))
>> +		data_block_counter = s->data_block_counter;
>>   	if (!(s->flags & CIP_DBC_IS_END_EVENT)) {
>>   		lost = data_block_counter != s->data_block_counter;
>>   	} else {
>
>These lines should be:
>
> > +	if (data_blocks == 0 && (s->flags & CIP_EMPTY_HAS_WRONG_DBC) &&
> > +         s->data_block_counter != UINT_MAX)
> > +		data_block_counter = s->data_block_counter;
>
>
>When CIP_SKIP_INIT_DBC_CHECK is enabled, initial value of 
>s->data_block_counter is set to UINT_MAX. An intention of this is to 
>skip detecting discontinuity for a first packet [31/44].
>
>This initial value has a bad effect when CIP_EMPTY_HAS_WRONG_DBC is
>enabled.
>
>A first packet is an empty packet. When this packet is handled, 
>data_block_counter is set to initial value of s->data_block_counter 
>(UINT_MAX). Later, s->data_block_counter is set to 0xff with bitmask in
>
>below lines.
>
>         if (s->flags & CIP_DBC_IS_END_EVENT)
>                 s->data_block_counter = data_block_counter;
>         else
>                 s->data_block_counter =
>                             (data_block_counter + data_blocks) & 0xff;
>
>When a packet with data blocks is handled later, s->data_block_counter 
>is 0xff, not UINT_MAX. This causes discontinuity detection because this
>
>packet has 0x00 in itx dbc in below lines.
>
>         if (lost && s->data_block_counter != UINT_MAX) {
>                 dev_info(&s->unit->device,
>                          "Detect discontinuity of CIP: %02X %02X\n",
>                          s->data_block_counter, data_block_counter);
>
>See this log:
>[ 2933.102892] 01020000 9002FFFF 02
>[ 2933.102894] 01020000 9002FFFF 02
>[ 2933.102896] 01020000 9002FFFF 02
>[ 2933.102899] 01020000 9002FFFF 02
>[ 2933.102901] 01020000 9002FFFF 02
>[ 2933.102903] 01020000 9002FFFF 02
>[ 2933.104871] 01110000 900258B5 8A
>[ 2933.104877] snd-bebob fw1.0: Detect discontinuity of CIP: FF 00
>
>I'm sorry to post a patch including a bug.
>
>
>Regards
>
>Takashi Sakamoto
>o-takashi@sakamocchi.jp
>
>
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