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Commit f91c9d76 authored by Takashi Sakamoto's avatar Takashi Sakamoto Committed by Takashi Iwai
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ALSA: firewire-lib: cache maximum length of payload to reduce function calls 



During packet streaming, maximum length of payload for isochronous packet
is invariable, therefore no need to recalculate. Current ALSA IEC 61883-1/6
engine calls a function to calculate it 8,000 or more times per second
for incoming packet processing.

This commit adds a member to have maximum length of payload into 'struct
amdtp_stream', to reduces the function calls. At first callback from
isochronous context, the length is calculated and stored for later
processing.

Signed-off-by: default avatarTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 12ee4022

sound/firewire/amdtp-stream.c

+5 −4
Original line number Diff line number Diff line
@@ -412,8 +412,7 @@ static inline int queue_out_packet(struct amdtp_stream *s, 


static inline int queue_in_packet(struct amdtp_stream *s)

{

	return queue_packet(s, IN_PACKET_HEADER_SIZE,

			    amdtp_stream_get_max_payload(s));

	return queue_packet(s, IN_PACKET_HEADER_SIZE, s->max_payload_length);

}



static int handle_out_packet(struct amdtp_stream *s,
@@ -713,12 +712,12 @@ static void in_stream_callback(struct fw_iso_context *context, u32 tstamp, 
	cycle = decrement_cycle_count(cycle, packets);



	/* For buffer-over-run prevention. */

	max_payload_length = amdtp_stream_get_max_payload(s);

	max_payload_length = s->max_payload_length;



	for (i = 0; i < packets; i++) {

		cycle = increment_cycle_count(cycle, 1);



		/* The number of quadlets in this packet */

		/* The number of bytes in this packet */

		payload_length =

			(be32_to_cpu(headers[i]) >> ISO_DATA_LENGTH_SHIFT);

		if (payload_length > max_payload_length) {
@@ -751,6 +750,8 @@ static void amdtp_stream_first_callback(struct fw_iso_context *context, 
	u32 cycle;

	unsigned int packets;



	s->max_payload_length = amdtp_stream_get_max_payload(s);



	/*

	 * For in-stream, first packet has come.

	 * For out-stream, prepared to transmit first packet

sound/firewire/amdtp-stream.h

+1 −0
Original line number Diff line number Diff line
@@ -110,6 +110,7 @@ struct amdtp_stream { 
	int (*handle_packet)(struct amdtp_stream *s,

			unsigned int payload_quadlets, unsigned int cycle,

			unsigned int index);

	unsigned int max_payload_length;



	/* For CIP headers. */

	unsigned int source_node_id_field;