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On most of audio and music units on IEEE 1394 bus which ALSA firewire stack
supports (or plans to support), CIP with two quadlets header is used.
Thus, there's no cases to queue packets with blank payload. If such packets
are going to be queued, it means that they're for skips of the cycle.
This commit simplifies helper functions to queue a packet.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Acked-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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In current implementation, packet processing is done in both of software
IRQ contexts of IR/IT contexts and process contexts.
This is usual interrupt handling of IR/IT context for 1394 OHCI.
(in hardware IRQ context)
irq_handler() (drivers/firewire/ohci.c)
->tasklet_schedule()
(in software IRQ context)
handle_it_packet() or handle_ir_packet_per_buffer() (drivers/firewire/ohci.c)
->flush_iso_completions()
->struct fw_iso_context.callback.sc()
= out_stream_callback() or in_stream_callback()
However, we have another chance for packet processing. It's done in PCM
frame handling via ALSA PCM interfaces.
(in process context)
ioctl(i.e. SNDRV_PCM_IOCTL_HWSYNC)
->snd_pcm_hwsync() (sound/core/pcm_native.c)
->snd_pcm_update_hw_ptr() (sound/core/pcm_lib.c)
->snd_pcm_update_hw_ptr0()
->struct snd_pcm_ops.pointer()
= amdtp_stream_pcm_pointer()
->fw_iso_context_flush_completions() (drivers/firewire/core-iso.c)
->struct fw_card_driver.flush_iso_completions()
= ohci_flush_iso_completions() (drivers/firewire/ohci.c)
->flush_iso_completions()
->struct fw_iso_context.callback.sc()
= out_stream_callback() or in_stream_callback()
This design is for a better granularity of PCM pointer. When ioctl(2) is
executed with some commands for ALSA PCM interface, queued packets are
handled at first. Then, the latest number of handled PCM frames is
reported. The number can represent PCM frames transferred in most near
isochronous cycle.
Current tracepoints include no information to distinguish running contexts.
When tracing the interval of software IRQ context, this is not good.
This commit adds more information for current context. Additionally, the
index of packet processed in one context is added in a case that packet
processing is executed in continuous context of the same kind,
As a result, the output includes 11 fields with additional two fields
to commit 0c95c1d6197f ("ALSA: firewire-lib: add tracepoints to dump a part
of isochronous packet data"):
17131.9186: out_packet: 07 7494 ffc0 ffc1 00 000700c0 9001a496 058 45 1 13
17131.9186: out_packet: 07 7495 ffc0 ffc1 00 000700c8 9001ba00 058 46 1 14
17131.9186: out_packet: 07 7496 ffc0 ffc1 00 000700d0 9001ffff 002 47 1 15
17131.9189: out_packet: 07 7497 ffc0 ffc1 00 000700d0 9001d36a 058 00 0 00
17131.9189: out_packet: 07 7498 ffc0 ffc1 00 000700d8 9001e8d4 058 01 0 01
17131.9189: out_packet: 07 7499 ffc0 ffc1 00 000700e0 9001023e 058 02 0 00
17131.9206: in_packet: 07 7447 ffc1 ffc0 01 3f070072 9001783d 058 32 1 00
17131.9206: in_packet: 07 7448 ffc1 ffc0 01 3f070072 90ffffff 002 33 1 01
17131.9206: in_packet: 07 7449 ffc1 ffc0 01 3f07007a 900191a8 058 34 1 02
(Here, some common fields are omitted so that a line is within 80
characters.)
The legend is:
- The second of cycle scheduled for the packet
- The count of cycle scheduled for the packet
- The ID of node as source (hex)
- The ID of node as destination (hex)
- The value of isochronous channel
- The first quadlet of CIP header (hex)
- The second quadlet of CIP header (hex)
- The number of included quadlets
- The index of packet in a buffer maintained by this module
- 0 in process context, 1 in IRQ context
- The index of packet processed in the context
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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for better PCM period granularity
These three commits were merged to improve PCM pointer granularity.
commit 76fb87894828 ("ALSA: firewire-lib: taskletize the snd_pcm_period_elapsed() call")
commit e9148dddc3c7 ("ALSA: firewire-lib: flush completed packets when reading PCM position")
commit 92b862c7d685 ("ALSA: firewire-lib: optimize packet flushing")
The point of them is to handle queued packets not only in software IRQ
context of IR/IT contexts, but also in process context. As a result of
handling packets, period tasklet is scheduled when acrossing PCM period
boundary. This is to prevent recursive call of
'struct snd_pcm_ops.pointer()' in the same context.
When the pointer callback is executed in the process context, it's
better to avoid the second callback in the software IRQ context. The
software IRQ context runs immediately after scheduled in the process
context because few packets are queued yet.
For the aim, 'pointer_flush' is used, however it causes a race condition
between the process context and software IRQ context of IR/IT contexts.
Practically, this race is not so critical because it influences process
context to skip flushing queued packet and to get worse granularity of
PCM pointer. The race condition is quite rare but it should be improved
for stable service.
The similar effect can be achieved by using 'in_interrupt()' macro. This
commit obsoletes 'pointer_flush' with it.
Acked-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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In former commit, drivers in ALSA firewire stack always starts IT context
before IR context. If IR context starts after packets are transmitted by
peer unit, packet discontinuity may be detected because the context starts
in the middle of packet streaming. This situation is rare because IT
context usually starts immediately. However, it's better to solve this
issue. This is suppressed with CIP_SKIP_INIT_DBC_CHECK flag.
This commit enables the same feature as CIP_SKIP_INIT_DBC_CHECK.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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In previous commit, this module has no need to reuse parameters of
incoming packets for outgoing packets anymore. This commit arranges some
needless codes for outgoing packet processing.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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In previous commit, this module has no need to reuse parameters of
incoming packets for outgoing packets anymore. This commit arranges some
needless codes for incoming packet processing.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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In clause 6.3 of IEC 61883-6:2000, there's an explanation about processing
of presentation timestamp. In the clause, we can see "If a function block
receives a CIP, processes it and subsequently re-transmits it, then the
SYT of the outgoing CIP shall be the sum of the incoming SYT and the
processing delay." ALSA firewire stack has an implementation to partly
satisfy this specification. Developers assumed the stack to perform as an
Audio function block[1].
Following to the assumption, current implementation of ALSA firewire stack
use one software interrupt context to handle both of in/out packets. In
most case, this is processed in 1394 OHCI IR context independently of the
opposite context. Thus, this implementation uses longer CPU time in the
software interrupt context. This is not better for whole system.
Against the assumption, I confirmed that each ASIC for IEC 61883-1/6
doesn't necessarily expect it to the stack. Thus, current implementation
of ALSA firewire stack includes over-engineering.
This commit purges the implementation. As a result, packets of one
direction are handled in one software interrupt context and spends
minimum CPU time.
[1] [alsa-devel] [PATCH 0/8] [RFC] new driver for Echo Audio's Fireworks based devices
http://mailman.alsa-project.org/pipermail/alsa-devel/2013-June/062660.html
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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When audio and music units have some quirks in their sequence of packet,
it's really hard for non-owners to identify the quirks. Although developers
need dumps for sequence of packets, it's difficult for users who have no
knowledges and no equipments for this purpose.
This commit adds tracepoints for this situation. When users encounter
the issue, they can dump a part of packet data via Linux tracing framework
as long as using drivers in ALSA firewire stack.
Additionally, tracepoints for outgoing packets will be our help to check
and debug packet processing of ALSA firewire stack.
This commit newly adds 'snd_firewire_lib' subsystem with 'in_packet' and
'out_packet' events. In the events, some attributes of packets and the
index of packet managed by this module are recorded per packet.
This is an usage:
$ trace-cmd record -e snd_firewire_lib:out_packet \
-e snd_firewire_lib:in_packet
/sys/kernel/tracing/events/snd_firewire_lib/out_packet/filter
/sys/kernel/tracing/events/snd_firewire_lib/in_packet/filter
Hit Ctrl^C to stop recording
^C
$ trace-cmd report trace.dat
...
23647.033934: in_packet: 01 4073 ffc0 ffc1 00 000f0040 9001b2d1 122 44
23647.033936: in_packet: 01 4074 ffc0 ffc1 00 000f0048 9001c83b 122 45
23647.033937: in_packet: 01 4075 ffc0 ffc1 00 000f0050 9001ffff 002 46
23647.033938: in_packet: 01 4076 ffc0 ffc1 00 000f0050 9001e1a6 122 47
23647.035426: out_packet: 01 4123 ffc1 ffc0 01 010f00d0 9001fb40 122 17
23647.035428: out_packet: 01 4124 ffc1 ffc0 01 010f00d8 9001ffff 002 18
23647.035429: out_packet: 01 4125 ffc1 ffc0 01 010f00d8 900114aa 122 19
23647.035430: out_packet: 01 4126 ffc1 ffc0 01 010f00e0 90012a15 122 20
(Here, some common fields are omitted so that a line to be within 80
characters.)
...
One line represent one packet. The legend for the last nine fields is:
- The second of cycle scheduled for the packet
- The count of cycle scheduled for the packet
- The ID of node as source (hex)
- Some devices transfer packets with invalid source node ID in their CIP
header.
- The ID of node as destination (hex)
- The value is not in CIP header of packets.
- The value of isochronous channel
- The first quadlet of CIP header (hex)
- The second quadlet of CIP header (hex)
- The number of included quadlets
- The index of packet in a buffer maintained by this module
This is an example to parse these lines from text file by Python3 script:
\#!/usr/bin/env python3
import sys
def parse_ts(second, cycle, syt):
offset = syt & 0xfff
syt >>= 12
if cycle & 0x0f > syt:
cycle += 0x10
cycle &= 0x1ff0
cycle |= syt
second += cycle // 8000
cycle %= 8000
# In CYCLE_TIMER of 1394 OHCI, second is represented in 8 bit.
second %= 128
return (second, cycle, offset)
def calc_ts(second, cycle, offset):
ts = offset
ts += cycle * 3072
# In DMA descriptor of 1394 OHCI, second is represented in 3 bit.
ts += (second % 8) * 8000 * 3072
return ts
def subtract_ts(minuend, subtrahend):
# In DMA descriptor of 1394 OHCI, second is represented in 3 bit.
if minuend < subtrahend:
minuend += 8 * 8000 * 3072
return minuend - subtrahend
if len(sys.argv) != 2:
print('At least, one argument is required for packet dump.')
sys.exit()
filename = sys.argv[1]
data = []
prev = 0
with open(filename, 'r') as f:
for line in f:
pos = line.find('packet:')
if pos < 0:
continue
pos += len('packet:')
line = line[pos:].strip()
fields = line.split(' ')
datum = []
datum.append(fields[8])
syt = int(fields[6][4:], 16)
# Empty packet in IEC 61883-1, or NODATA in IEC 61883-6
if syt == 0xffff:
data_blocks = 0
else:
payload_size = int(fields[7], 10)
data_block_size = int(fields[5][2:4], 16)
data_blocks = (payload_size - 2) / data_block_size
datum.append(data_blocks)
second = int(fields[0], 10)
cycle = int(fields[1], 10)
start = (second << 25) | (cycle << 12)
datum.append('0x{0:08x}'.format(start))
start = calc_ts(second, cycle, 0)
datum.append("0x" + fields[5])
datum.append("0x" + fields[6])
if syt == 0xffff:
second = 0
cycle = 0
tick = 0
else:
second, cycle, tick = parse_ts(second, cycle, syt)
ts = calc_ts(second, cycle, tick)
datum.append(start)
datum.append(ts)
if ts == 0:
datum.append(0)
datum.append(0)
else:
# Usual case, or a case over 8 seconds.
if ts > start or start > 7 * 8000 * 3072:
datum.append(subtract_ts(ts, start))
if ts > prev or start > 7 * 8000 * 3072:
gap = subtract_ts(ts, prev)
datum.append(gap)
else:
datum.append('backward')
else:
datum.append('invalid')
prev = ts
data.append(datum)
sys.exit()
The data variable includes array with these elements:
- The index of the packet
- The number of data blocks in the packet
- The value of cycle count (hex)
- The value of CIP header 1 (hex)
- The value of CIP header 2 (hex)
- The value of cycle count (tick)
- The value of calculated presentation timestamp (tick)
- The offset between the cycle count and presentation timestamp
- The elapsed ticks from the previous presentation timestamp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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context
In callback function of isochronous context, modules can queue packets to
indicated isochronous cycles. Although the cycle to queue a packet is
deterministic by calculation, this module doesn't implement the calculation
because it's useless for processing.
In future, the cycle count is going to be printed with the other parameters
for debugging. This commit is the preparation. The cycle count is computed
by cycle unit, and correctly arranged to corresponding packets. The
calculated count is used in later commit.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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context
In callback function of isochronous context, u32 variable is passed for
cycle count. The value of this variable comes from DMA descriptors of 1394
Open Host Controller Interface (1394 OHCI). In the specification, DMA
descriptors transport lower 3 bits for second field and full cycle field in
16 bits field, therefore 16 bits of the u32 variable are available. The
value for second is modulo 8, and the value for cycle is modulo 8,000.
Currently, ALSA firewire-lib module don't use the value of the second
field, because the value is useless to calculate presentation timestamp in
IEC 61883-6. However, the value may be useful for debugging. In later
commit, it will be printed with the other parameters for debugging.
This commit makes this module to handle the whole cycle count including
second. The value is calculated by cycle unit. The existed code is already
written with ignoring the value of second, thus this commit causes no
issues.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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stream data
When any of AMDTP stream data are not initialized and private data is
going to be released, WARN_ON() in amdtp_stream_destroy() is hit and
dump messages. This may take users irritated.
This commit fixes the bug to skip releasing when it's not initialized.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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In firewire-lib, isochronous packet streaming is stopped when detecting
wrong value for FMT field of CIP headers. Although this is appropriate
to IEC 61883-1 and 6, some BeBoB based devices with vendors' customization
use invalid value to FMT field of CIP headers in the beginning of
streaming.
$ journalctl
snd-bebob fw1.0: Detect unexpected protocol: 01000000 8000ffff
I got this log with M-Audio FireWire 1814. In this line, the value of FMT
field is 0x00, while it should be 0x10 in usual AMDTP.
Except for the beginning, these devices continue to transfer packets with
valid value for FMT field, except for the beginning. Therefore, in this
case, firewire-lib should continue to process packets. The former
implementation of firewire-lib performs it.
This commit loosens the handling of wrong value, to continue packet
processing in the case.
Fixes: 414ba022a528 ('ALSA: firewire-lib: add support arbitrary value for fmt/fdf fields in CIP header')
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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This commit moves the codes related to data block processing from packet
streaming layer to AM824 layer.
Each driver initializes amdtp stream structure for AM824 data block by
calling amdtp_am824_init(). Then, a memory block is allocated for AM824
specific structure. This memory block is released by calling
amdtp_stream_destroy().
When setting streaming parameters, it calls amdtp_am824_set_parameters().
When starting packet streaming, it calls amdtp_stream_start(). When
stopping packet streaming, it calls amdtp_stream_stop().
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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This commit renames some macros just related to AM824 format. In later
commit, they're moved to AM824 layer.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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Setting the format of PCM substream to AMDTP stream structure is important
to set a handler to copy actual PCM samples between buffers. The
processing should be in data block processing layer because essentially
it has no relationship to packet streaming.
This commit renames PCM format setting function to prepare for integrating
AM824 layer.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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In IEC 61883-6, PCM frames are transferred in Multi Bit Linear Audio data
channel. The data channel transfers 16/20/24 bit PCM samples. Thus, PCM
substream has a constrain about it.
This commit moves codes related to the constraint from packet streaming
layer to AM824 data block processing layer.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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The value of FDF field in CIP header is protocol-dependent. Thus, it's
better to allow data block processing layer to decide the value in any
timing.
In AM824 data format, the value of FDF field in CIP header indicates
N-flag and Nominal Sampling Frequency Code (sfc). The N-flag is for
switching 'Clock-based rate control mode' and 'Command-based rate control
mode'. In our implementation, 'Clock-based rate control mode' is just
supported. Therefore, When sampling transfer frequency is decided, then
the FDF can be set.
This commit replaces 'amdtp_stream_set_parameters' with
'amdtp_am824_set_parameters' to set the FDF. This is the same timing
to decide the ration between the number of data blocks and the number of
PCM frames.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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This commit adds data block processing layer for AM824 format. The new
layer initializes streaming layer with its value for fmt field.
Currently, most implementation of data block processing still remains
streaming layer. In later commits, these codes will be moved to the layer.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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functional separation
In later commit, data block processing layer will be newly added. This
layer will be named as 'amdtp-am824'.
This commit renames current amdtp file to amdtp-stream, to distinguish it
from the new layer.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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