[alsa-devel] [PATCH 09/14] ALSA: firewire-lib: add no-header packet processing
Takashi Sakamoto
o-takashi at sakamocchi.jp
Fri Mar 31 15:06:07 CEST 2017
As long as investigating Fireface 400, IEC 61883-1/6 is not applied to
its packet streaming protocol. Remarks of the specific protocol are:
* Each packet doesn't include CIP headers.
* 64,0 and 128,0 kHz are supported.
* The device doesn't necessarily transmit 8,000 packets per second.
* 0, 1, 2, 3 are used as tag for rx isochronous packets, however 0 is
used for tx isochronous packets.
On the other hand, there's a common feature. The number of data blocks
transferred in a second is the same as sampling transmission frequency.
Current ALSA IEC 61883-1/6 engine already has a method to calculate it and
this driver can utilize it for rx packets, as well as tx packets.
This commit adds support for the transferring protocol. CIP_NO_HEADERS
flag is newly added. When this flag is set:
* Both of 0 (without CIP header) and 1 (with CIP header) are used as tag
to handle incoming isochronous packet.
* 0 (without CIP header) is used as tag to transfer outgoing isochronous
packet.
* Skip CIP header evaluation.
* Use unique way to calculate the quadlets of isochronous packet payload.
In ALSA PCM interface, 128.0 kHz is not supported, and the ALSA
IEC 61883-1/6 engine doesn't support 64.0 kHz. These modes are dropped.
The sequence of rx packet has a remarkable quirk about tag. This will be
described in later commits.
Signed-off-by: Takashi Sakamoto <o-takashi at sakamocchi.jp>
---
sound/firewire/amdtp-stream.c | 80 ++++++++++++++++++++++++++++++++++++++++---
sound/firewire/amdtp-stream.h | 6 ++++
2 files changed, 81 insertions(+), 5 deletions(-)
diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c
index 646e8e3..a03b37b 100644
--- a/sound/firewire/amdtp-stream.c
+++ b/sound/firewire/amdtp-stream.c
@@ -27,6 +27,7 @@
/* isochronous header parameters */
#define ISO_DATA_LENGTH_SHIFT 16
+#define TAG_NO_CIP_HEADER 0
#define TAG_CIP 1
/* common isochronous packet header parameters */
@@ -234,11 +235,15 @@ EXPORT_SYMBOL(amdtp_stream_set_parameters);
unsigned int amdtp_stream_get_max_payload(struct amdtp_stream *s)
{
unsigned int multiplier = 1;
+ unsigned int header_size = 0;
if (s->flags & CIP_JUMBO_PAYLOAD)
multiplier = 5;
+ if (!(s->flags & CIP_NO_HEADER))
+ header_size = 8;
- return 8 + s->syt_interval * s->data_block_quadlets * 4 * multiplier;
+ return header_size +
+ s->syt_interval * s->data_block_quadlets * 4 * multiplier;
}
EXPORT_SYMBOL(amdtp_stream_get_max_payload);
@@ -380,7 +385,7 @@ static int queue_packet(struct amdtp_stream *s, unsigned int header_length,
goto end;
p.interrupt = IS_ALIGNED(s->packet_index + 1, INTERRUPT_INTERVAL);
- p.tag = TAG_CIP;
+ p.tag = s->tag;
p.header_length = header_length;
if (payload_length > 0)
p.payload_length = payload_length;
@@ -457,6 +462,34 @@ static int handle_out_packet(struct amdtp_stream *s,
return 0;
}
+static int handle_out_packet_without_header(struct amdtp_stream *s,
+ unsigned int payload_length, unsigned int cycle,
+ unsigned int index)
+{
+ __be32 *buffer;
+ unsigned int syt;
+ unsigned int data_blocks;
+ unsigned int pcm_frames;
+ struct snd_pcm_substream *pcm;
+
+ buffer = s->buffer.packets[s->packet_index].buffer;
+ syt = calculate_syt(s, cycle);
+ data_blocks = calculate_data_blocks(s, syt);
+ pcm_frames = s->process_data_blocks(s, buffer, data_blocks, &syt);
+ s->data_block_counter = (s->data_block_counter + data_blocks) & 0xff;
+
+ payload_length = data_blocks * 4 * s->data_block_quadlets;
+ if (queue_out_packet(s, payload_length) < 0)
+ return -EIO;
+
+ pcm = ACCESS_ONCE(s->pcm);
+ if (pcm && pcm_frames > 0)
+ update_pcm_pointers(s, pcm, pcm_frames);
+
+ /* No need to return the number of handled data blocks. */
+ return 0;
+}
+
static int handle_in_packet(struct amdtp_stream *s,
unsigned int payload_length, unsigned int cycle,
unsigned int index)
@@ -573,6 +606,30 @@ static int handle_in_packet(struct amdtp_stream *s,
return 0;
}
+static int handle_in_packet_without_header(struct amdtp_stream *s,
+ unsigned int payload_quadlets, unsigned int cycle,
+ unsigned int index)
+{
+ __be32 *buffer;
+ unsigned int data_blocks;
+ struct snd_pcm_substream *pcm;
+ unsigned int pcm_frames;
+
+ buffer = s->buffer.packets[s->packet_index].buffer;
+ data_blocks = payload_quadlets / s->data_block_quadlets;
+ pcm_frames = s->process_data_blocks(s, buffer, data_blocks, NULL);
+ s->data_block_counter = (s->data_block_counter + data_blocks) & 0xff;
+
+ if (queue_in_packet(s) < 0)
+ return -EIO;
+
+ pcm = ACCESS_ONCE(s->pcm);
+ if (pcm && pcm_frames > 0)
+ update_pcm_pointers(s, pcm, pcm_frames);
+
+ return 0;
+}
+
/*
* In CYCLE_TIMER register of IEEE 1394, 7 bits are used to represent second. On
* the other hand, in DMA descriptors of 1394 OHCI, 3 bits are used to represent
@@ -616,7 +673,7 @@ static void out_stream_callback(struct fw_iso_context *context, u32 tstamp,
for (i = 0; i < packets; ++i) {
cycle = increment_cycle_count(cycle, 1);
- if (handle_out_packet(s, 0, cycle, i) < 0) {
+ if (s->handle_packet(s, 0, cycle, i) < 0) {
s->packet_index = -1;
amdtp_stream_pcm_abort(s);
return;
@@ -663,7 +720,7 @@ static void in_stream_callback(struct fw_iso_context *context, u32 tstamp,
break;
}
- if (handle_in_packet(s, payload_length, cycle, i) < 0)
+ if (s->handle_packet(s, payload_length, cycle, i) < 0)
break;
}
@@ -699,10 +756,18 @@ static void amdtp_stream_first_callback(struct fw_iso_context *context,
packets = header_length / IN_PACKET_HEADER_SIZE;
cycle = decrement_cycle_count(cycle, packets);
context->callback.sc = in_stream_callback;
+ if (s->flags & CIP_NO_HEADER)
+ s->handle_packet = handle_in_packet_without_header;
+ else
+ s->handle_packet = handle_in_packet;
} else {
packets = header_length / 4;
cycle = increment_cycle_count(cycle, QUEUE_LENGTH - packets);
context->callback.sc = out_stream_callback;
+ if (s->flags & CIP_NO_HEADER)
+ s->handle_packet = handle_out_packet_without_header;
+ else
+ s->handle_packet = handle_out_packet;
}
s->start_cycle = cycle;
@@ -782,6 +847,11 @@ int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed)
amdtp_stream_update(s);
+ if (s->flags & CIP_NO_HEADER)
+ s->tag = TAG_NO_CIP_HEADER;
+ else
+ s->tag = TAG_CIP;
+
s->packet_index = 0;
do {
if (s->direction == AMDTP_IN_STREAM)
@@ -794,7 +864,7 @@ int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed)
/* NOTE: TAG1 matches CIP. This just affects in stream. */
tag = FW_ISO_CONTEXT_MATCH_TAG1;
- if (s->flags & CIP_EMPTY_WITH_TAG0)
+ if ((s->flags & CIP_EMPTY_WITH_TAG0) || (s->flags & CIP_NO_HEADER))
tag |= FW_ISO_CONTEXT_MATCH_TAG0;
s->callbacked = false;
diff --git a/sound/firewire/amdtp-stream.h b/sound/firewire/amdtp-stream.h
index a31dfd8..2bd4de4 100644
--- a/sound/firewire/amdtp-stream.h
+++ b/sound/firewire/amdtp-stream.h
@@ -31,6 +31,7 @@
* allows 5 times as large as IEC 61883-6 defines.
* @CIP_HEADER_WITHOUT_EOH: Only for in-stream. CIP Header doesn't include
* valid EOH.
+ * @CIP_NO_HEADERS: a lack of headers in packets
*/
enum cip_flags {
CIP_NONBLOCKING = 0x00,
@@ -42,6 +43,7 @@ enum cip_flags {
CIP_EMPTY_HAS_WRONG_DBC = 0x20,
CIP_JUMBO_PAYLOAD = 0x40,
CIP_HEADER_WITHOUT_EOH = 0x80,
+ CIP_NO_HEADER = 0x100,
};
/**
@@ -104,6 +106,10 @@ struct amdtp_stream {
struct fw_iso_context *context;
struct iso_packets_buffer buffer;
int packet_index;
+ int tag;
+ int (*handle_packet)(struct amdtp_stream *s,
+ unsigned int payload_quadlets, unsigned int cycle,
+ unsigned int index);
/* For CIP headers. */
unsigned int source_node_id_field;
--
2.9.3
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