ALSA: firewire-lib: handle quirk to calculate payload quadlets as data block counter

Miglia Harmony Audio (OXFW970) has a quirk to put the number of
accumulated quadlets in CIP payload into the dbc field of CIP header.

This commit handles the quirk in the packet processing layer.

Signed-off-by: Takashi Sakamoto <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Takashi Iwai <[e-mail]>

sound/firewire/amdtp-stream.c

···
 	} else {
 		unsigned int dbc_interval;
 
-		if (*data_blocks > 0 && s->ctx_data.tx.dbc_interval > 0)
-			dbc_interval = s->ctx_data.tx.dbc_interval;
-		else
-			dbc_interval = *data_blocks;
+		if (!(s->flags & CIP_DBC_IS_PAYLOAD_QUADLETS)) {
+			if (*data_blocks > 0 && s->ctx_data.tx.dbc_interval > 0)
+				dbc_interval = s->ctx_data.tx.dbc_interval;
+			else
+				dbc_interval = *data_blocks;
+		} else {
+			dbc_interval = payload_length / sizeof(__be32);
+		}
 
 		lost = dbc != ((*data_block_counter + dbc_interval) & 0xff);
 	}

sound/firewire/amdtp-stream.h

···
  *	the value of current SYT_INTERVAL; e.g. initial value is not zero.
  * @CIP_UNAWARE_SYT: For outgoing packet, the value in SYT field of CIP is 0xffff.
  *	For incoming packet, the value in SYT field of CIP is not handled.
+ * @CIP_DBC_IS_PAYLOAD_QUADLETS: Available for incoming packet, and only effective with
+ *	CIP_DBC_IS_END_EVENT flag. The value of dbc field is the number of accumulated quadlets
+ *	in CIP payload, instead of the number of accumulated data blocks.
  */
 enum cip_flags {
 	CIP_NONBLOCKING		= 0x00,
···
 	CIP_NO_HEADER		= 0x100,
 	CIP_UNALIGHED_DBC	= 0x200,
 	CIP_UNAWARE_SYT		= 0x400,
+	CIP_DBC_IS_PAYLOAD_QUADLETS = 0x800,
 };
 
 /**