From f91c9d7610a2fe306273a83e2fd5351bceb85d28 Mon Sep 17 00:00:00 2001 From: Takashi Sakamoto Date: Tue, 11 Apr 2017 20:33:18 +0900 Subject: [PATCH] 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: Takashi Sakamoto Signed-off-by: Takashi Iwai --- sound/firewire/amdtp-stream.c | 9 +++++---- sound/firewire/amdtp-stream.h | 1 + 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c index f6af8e64c2cd..9e6f54f8c45d 100644 --- a/sound/firewire/amdtp-stream.c +++ b/sound/firewire/amdtp-stream.c @@ -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 diff --git a/sound/firewire/amdtp-stream.h b/sound/firewire/amdtp-stream.h index 2bd4de4c7bb7..7e8831722821 100644 --- a/sound/firewire/amdtp-stream.h +++ b/sound/firewire/amdtp-stream.h @@ -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;