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  1. 02 10月, 2018 1 次提交
    • T
      ALSA: firewire-lib: add PCM rules to obsolete PCM constraints based on LCM of SYT_INTERVAL · 59502295
      由 Takashi Sakamoto 提交于 
      In blocking mode of IEC 61883-1/6, when one isochronous packet includes
data for events, the data is for the same number of events as
SYT_INTERVAL decided according to sampling transmission frequency (SFC).

IEC 61883-1/6 engine of ALSA firewire stack applies constraints of
period and buffer size of PCM intermediate buffer of PCM substream.
At present, this constraint is designed to round the size up/down to
32 frames. This value comes from the least common multiple (LCM) of
SYT_INTERVAL. Although this looks to work well, in lower sampling
rate, applications are not allowed to set size of period quite near
period time constraint (at present 5 msec per period).

This commit adds PCM rules for period/buffer size and rate to obsoletes
the constraints based on LCM.
Signed-off-by: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
      59502295
  3. 29 4月, 2018 1 次提交
    • T
      ALSA: dice: fix kernel NULL pointer dereference due to invalid calculation for array index · 52759c09
      由 Takashi Sakamoto 提交于 
      At a commit f91c9d76 ('ALSA: firewire-lib: cache maximum length of
payload to reduce function calls'), maximum size of payload for tx
isochronous packet is cached to reduce the number of function calls.

This cache was programmed to updated at a first callback of ohci1394 IR
context. However, the maximum size is required to queueing packets before
starting the isochronous context.

As a result, the cached value is reused to queue packets in next time to
starting the isochronous context. Then the cache is updated in a first
callback of the isochronous context. This can cause kernel NULL pointer
dereference in a below call graph:

(sound/firewire/amdtp-stream.c)
amdtp_stream_start()
->queue_in_packet()
  ->queue_packet()
    (drivers/firewire/core-iso.c)
    ->fw_iso_context_queue()
      ->struct fw_card_driver.queue_iso()
      (drivers/firewire/ohci.c)
      = ohci_queue_iso()
        ->queue_iso_packet_per_buffer()
          buffer->pages[page]

The issued dereference occurs in a case that:
 - target unit supports different stream formats for sampling transmission
   frequency.
 - maximum length of payload for tx stream in a first trial is bigger
   than the length in a second trial.

In this case, correct number of pages are allocated for DMA and the 'pages'
array has enough elements, while index of the element is wrongly calculated
according to the old value of length of payload in a call of
'queue_in_packet()'. Then it causes the issue.

This commit fixes the critical bug. This affects all of drivers in ALSA
firewire stack in Linux kernel v4.12 or later.

[12665.302360] BUG: unable to handle kernel NULL pointer dereference at 0000000000000030
[12665.302415] IP: ohci_queue_iso+0x47c/0x800 [firewire_ohci]
[12665.302439] PGD 0
[12665.302440] P4D 0
[12665.302450]
[12665.302470] Oops: 0000 [#1] SMP PTI
[12665.302487] Modules linked in: ...
[12665.303096] CPU: 1 PID: 12760 Comm: jackd Tainted: P           OE   4.13.0-38-generic #43-Ubuntu
[12665.303154] Hardware name:                  /DH77DF, BIOS KCH7710H.86A.0069.2012.0224.1825 02/24/2012
[12665.303215] task: ffff9ce87da2ae80 task.stack: ffffb5b8823d0000
[12665.303258] RIP: 0010:ohci_queue_iso+0x47c/0x800 [firewire_ohci]
[12665.303301] RSP: 0018:ffffb5b8823d3ab8 EFLAGS: 00010086
[12665.303337] RAX: ffff9ce4f4876930 RBX: 0000000000000008 RCX: ffff9ce88a3955e0
[12665.303384] RDX: 0000000000000000 RSI: 0000000034877f00 RDI: 0000000000000000
[12665.303427] RBP: ffffb5b8823d3b68 R08: ffff9ce8ccb390a0 R09: ffff9ce877639ab0
[12665.303475] R10: 0000000000000108 R11: 0000000000000000 R12: 0000000000000003
[12665.303513] R13: 0000000000000000 R14: ffff9ce4f4876950 R15: 0000000000000000
[12665.303554] FS:  00007f2ec467f8c0(0000) GS:ffff9ce8df280000(0000) knlGS:0000000000000000
[12665.303600] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[12665.303633] CR2: 0000000000000030 CR3: 00000002dcf90004 CR4: 00000000000606e0
[12665.303674] Call Trace:
[12665.303698]  fw_iso_context_queue+0x18/0x20 [firewire_core]
[12665.303735]  queue_packet+0x88/0xe0 [snd_firewire_lib]
[12665.303770]  amdtp_stream_start+0x19b/0x270 [snd_firewire_lib]
[12665.303811]  start_streams+0x276/0x3c0 [snd_dice]
[12665.303840]  snd_dice_stream_start_duplex+0x1bf/0x480 [snd_dice]
[12665.303882]  ? vma_gap_callbacks_rotate+0x1e/0x30
[12665.303914]  ? __rb_insert_augmented+0xab/0x240
[12665.303936]  capture_prepare+0x3c/0x70 [snd_dice]
[12665.303961]  snd_pcm_do_prepare+0x1d/0x30 [snd_pcm]
[12665.303985]  snd_pcm_action_single+0x3b/0x90 [snd_pcm]
[12665.304009]  snd_pcm_action_nonatomic+0x68/0x70 [snd_pcm]
[12665.304035]  snd_pcm_prepare+0x68/0x90 [snd_pcm]
[12665.304058]  snd_pcm_common_ioctl1+0x4c0/0x940 [snd_pcm]
[12665.304083]  snd_pcm_capture_ioctl1+0x19b/0x250 [snd_pcm]
[12665.304108]  snd_pcm_capture_ioctl+0x27/0x40 [snd_pcm]
[12665.304131]  do_vfs_ioctl+0xa8/0x630
[12665.304148]  ? entry_SYSCALL_64_after_hwframe+0xe9/0x139
[12665.304172]  ? entry_SYSCALL_64_after_hwframe+0xe2/0x139
[12665.304195]  ? entry_SYSCALL_64_after_hwframe+0xdb/0x139
[12665.304218]  ? entry_SYSCALL_64_after_hwframe+0xd4/0x139
[12665.304242]  ? entry_SYSCALL_64_after_hwframe+0xcd/0x139
[12665.304265]  ? entry_SYSCALL_64_after_hwframe+0xc6/0x139
[12665.304288]  ? entry_SYSCALL_64_after_hwframe+0xbf/0x139
[12665.304312]  ? entry_SYSCALL_64_after_hwframe+0xb8/0x139
[12665.304335]  ? entry_SYSCALL_64_after_hwframe+0xb1/0x139
[12665.304358]  SyS_ioctl+0x79/0x90
[12665.304374]  ? entry_SYSCALL_64_after_hwframe+0x72/0x139
[12665.304397]  entry_SYSCALL_64_fastpath+0x24/0xab
[12665.304417] RIP: 0033:0x7f2ec3750ef7
[12665.304433] RSP: 002b:00007fff99e31388 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[12665.304465] RAX: ffffffffffffffda RBX: 00007fff99e312f0 RCX: 00007f2ec3750ef7
[12665.304494] RDX: 0000000000000000 RSI: 0000000000004140 RDI: 0000000000000007
[12665.304522] RBP: 0000556ebc63fd60 R08: 0000556ebc640560 R09: 0000000000000000
[12665.304553] R10: 0000000000000001 R11: 0000000000000246 R12: 0000556ebc63fcf0
[12665.304584] R13: 0000000000000000 R14: 0000000000000007 R15: 0000000000000000
[12665.304612] Code: 01 00 00 44 89 eb 45 31 ed 45 31 db 66 41 89 1e 66 41 89 5e 0c 66 45 89 5e 0e 49 8b 49 08 49 63 d4 4d 85 c0 49 63 ff 48 8b 14 d1 <48> 8b 72 30 41 8d 14 37 41 89 56 04 48 63 d3 0f 84 ce 00 00 00
[12665.304713] RIP: ohci_queue_iso+0x47c/0x800 [firewire_ohci] RSP: ffffb5b8823d3ab8
[12665.304743] CR2: 0000000000000030
[12665.317701] ---[ end trace 9d55b056dd52a19f ]---

Fixes: f91c9d76 ('ALSA: firewire-lib: cache maximum length of payload to reduce function calls')
Cc: <stable@vger.kernel.org> # v4.12+
Signed-off-by: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
      52759c09
  5. 25 10月, 2017 1 次提交
    • M
      locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns... · 6aa7de05
      由 Mark Rutland 提交于 
      locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE()

Please do not apply this to mainline directly, instead please re-run the
coccinelle script shown below and apply its output.

For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't harmful, and changing them results in
churn.

However, for some features, the read/write distinction is critical to
correct operation. To distinguish these cases, separate read/write
accessors must be used. This patch migrates (most) remaining
ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following
coccinelle script:

----
// Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and
// WRITE_ONCE()

// $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch

virtual patch

@ depends on patch @
expression E1, E2;
@@

- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)

@ depends on patch @
expression E;
@@

- ACCESS_ONCE(E)
+ READ_ONCE(E)
----
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: shuah@kernel.org
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      6aa7de05
  7. 19 6月, 2017 1 次提交
    • T
      ALSA: firewire-lib: Fix stall of process context at packet error · 4a9bfafc
      由 Takashi Sakamoto 提交于 
      At Linux v3.5, packet processing can be done in process context of ALSA
PCM application as well as software IRQ context for OHCI 1394. Below is
an example of the callgraph (some calls are omitted).

ioctl(2) with e.g. HWSYNC
(sound/core/pcm_native.c)
->snd_pcm_common_ioctl1()
  ->snd_pcm_hwsync()
    ->snd_pcm_stream_lock_irq
    (sound/core/pcm_lib.c)
    ->snd_pcm_update_hw_ptr()
      ->snd_pcm_udpate_hw_ptr0()
        ->struct snd_pcm_ops.pointer()
        (sound/firewire/*)
        = Each handler on drivers in ALSA firewire stack
          (sound/firewire/amdtp-stream.c)
          ->amdtp_stream_pcm_pointer()
            (drivers/firewire/core-iso.c)
            ->fw_iso_context_flush_completions()
              ->struct fw_card_driver.flush_iso_completion()
              (drivers/firewire/ohci.c)
              = flush_iso_completions()
                ->struct fw_iso_context.callback.sc
                (sound/firewire/amdtp-stream.c)
                = in_stream_callback() or out_stream_callback()
                  ->...
    ->snd_pcm_stream_unlock_irq

When packet queueing error occurs or detecting invalid packets in
'in_stream_callback()' or 'out_stream_callback()', 'snd_pcm_stop_xrun()'
is called on local CPU with disabled IRQ.

(sound/firewire/amdtp-stream.c)
in_stream_callback() or out_stream_callback()
->amdtp_stream_pcm_abort()
  ->snd_pcm_stop_xrun()
    ->snd_pcm_stream_lock_irqsave()
    ->snd_pcm_stop()
    ->snd_pcm_stream_unlock_irqrestore()

The process is stalled on the CPU due to attempt to acquire recursive lock.

[  562.630853] INFO: rcu_sched detected stalls on CPUs/tasks:
[  562.630861]      2-...: (1 GPs behind) idle=37d/140000000000000/0 softirq=38323/38323 fqs=7140
[  562.630862]      (detected by 3, t=15002 jiffies, g=21036, c=21035, q=5933)
[  562.630866] Task dump for CPU 2:
[  562.630867] alsa-source-OXF R  running task        0  6619      1 0x00000008
[  562.630870] Call Trace:
[  562.630876]  ? vt_console_print+0x79/0x3e0
[  562.630880]  ? msg_print_text+0x9d/0x100
[  562.630883]  ? up+0x32/0x50
[  562.630885]  ? irq_work_queue+0x8d/0xa0
[  562.630886]  ? console_unlock+0x2b6/0x4b0
[  562.630888]  ? vprintk_emit+0x312/0x4a0
[  562.630892]  ? dev_vprintk_emit+0xbf/0x230
[  562.630895]  ? do_sys_poll+0x37a/0x550
[  562.630897]  ? dev_printk_emit+0x4e/0x70
[  562.630900]  ? __dev_printk+0x3c/0x80
[  562.630903]  ? _raw_spin_lock+0x20/0x30
[  562.630909]  ? snd_pcm_stream_lock+0x31/0x50 [snd_pcm]
[  562.630914]  ? _snd_pcm_stream_lock_irqsave+0x2e/0x40 [snd_pcm]
[  562.630918]  ? snd_pcm_stop_xrun+0x16/0x70 [snd_pcm]
[  562.630922]  ? in_stream_callback+0x3e6/0x450 [snd_firewire_lib]
[  562.630925]  ? handle_ir_packet_per_buffer+0x8e/0x1a0 [firewire_ohci]
[  562.630928]  ? ohci_flush_iso_completions+0xa3/0x130 [firewire_ohci]
[  562.630932]  ? fw_iso_context_flush_completions+0x15/0x20 [firewire_core]
[  562.630935]  ? amdtp_stream_pcm_pointer+0x2d/0x40 [snd_firewire_lib]
[  562.630938]  ? pcm_capture_pointer+0x19/0x20 [snd_oxfw]
[  562.630943]  ? snd_pcm_update_hw_ptr0+0x47/0x3d0 [snd_pcm]
[  562.630945]  ? poll_select_copy_remaining+0x150/0x150
[  562.630947]  ? poll_select_copy_remaining+0x150/0x150
[  562.630952]  ? snd_pcm_update_hw_ptr+0x10/0x20 [snd_pcm]
[  562.630956]  ? snd_pcm_hwsync+0x45/0xb0 [snd_pcm]
[  562.630960]  ? snd_pcm_common_ioctl1+0x1ff/0xc90 [snd_pcm]
[  562.630962]  ? futex_wake+0x90/0x170
[  562.630966]  ? snd_pcm_capture_ioctl1+0x136/0x260 [snd_pcm]
[  562.630970]  ? snd_pcm_capture_ioctl+0x27/0x40 [snd_pcm]
[  562.630972]  ? do_vfs_ioctl+0xa3/0x610
[  562.630974]  ? vfs_read+0x11b/0x130
[  562.630976]  ? SyS_ioctl+0x79/0x90
[  562.630978]  ? entry_SYSCALL_64_fastpath+0x1e/0xad

This commit fixes the above bug. This assumes two cases:
1. Any error is detected in software IRQ context of OHCI 1394 context.
In this case, PCM substream should be aborted in packet handler. On the
other hand, it should not be done in any process context. TO distinguish
these two context, use 'in_interrupt()' macro.
2. Any error is detect in process context of ALSA PCM application.
In this case, PCM substream should not be aborted in packet handler
because PCM substream lock is acquired. The task to abort PCM substream
should be done in ALSA PCM core. For this purpose, SNDRV_PCM_POS_XRUN is
returned at 'struct snd_pcm_ops.pointer()'.
Suggested-by: NClemens Ladisch <clemens@ladisch.de>
Fixes: e9148ddd("ALSA: firewire-lib: flush completed packets when reading PCM position")
Cc: <stable@vger.kernel.org> # 4.9+
Signed-off-by: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
      4a9bfafc
  9. 08 6月, 2017 1 次提交
  11. 07 6月, 2017 1 次提交
    • T
      ALSA: firewire: process packets in 'struct snd_pcm_ops.ack' callback · 875becf8
      由 Takashi Sakamoto 提交于 
      In recent commit for ALSA PCM core, some arrangement is done for
'struct snd_pcm_ops.ack' callback. This is called when appl_ptr is
explicitly moved in intermediate buffer for PCM frames, except for
some cases described later.

For drivers in ALSA firewire stack, usage of this callback has a merit to
reduce latency between time of PCM frame queueing and handling actual
packets in recent isochronous cycle, because no need to wait for software
IRQ context from isochronous context of OHCI 1394.

If this works well in a case that mapped page frame is used for the
intermediate buffer, user process should execute some commands for ioctl(2)
to tell the number of handled PCM frames in the intermediate buffer just
after handling them. Therefore, at present, with a combination of below
conditions, this doesn't work as expected and user process should wait for
the software IRQ context as usual:
 - when ALSA PCM core judges page frame mapping is available for status
   data (struct snd_pcm_mmap_status) and control data
   (struct snd_pcm_mmap_control).
 - user process handles PCM frames by loop just with 'snd_pcm_mmap_begin()'
   and 'snd_pcm_mmap_commit()'.
 - user process uses PCM hw plugin in alsa-lib to operate I/O without
   'sync_ptr_ioctl' option.

Unfortunately, major use case include these three conditions.
Signed-off-by: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
      875becf8
  13. 12 4月, 2017 1 次提交
  15. 11 4月, 2017 1 次提交
  17. 06 4月, 2017 2 次提交
    • T
      ALSA: firewire-lib: add no-header packet processing · 3b196c39
      由 Takashi Sakamoto 提交于 
      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: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
      3b196c39
    • T
      ALSA: firewire-lib: use the same prototype for functions to handle packet · ff0fb5aa
      由 Takashi Sakamoto 提交于 
      Audio and music units of RME Fireface series use its own protocol for
isochronous packets to transfer data. This protocol requires ALSA IEC
61883-1/6 engine to have alternative functions.

This commit is a preparation for the protocol.
Signed-off-by: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
      ff0fb5aa
  19. 28 3月, 2017 4 次提交
  21. 05 1月, 2017 1 次提交
    • T
      Revert "ALSA: firewire-lib: change structure member with proper type" · e4f34cf6
      由 Takashi Sakamoto 提交于 
      This reverts commit 6b7e95d1. This commit
is based on a concern about value of the given parameter. It's expected
to be ORed value with some enumeration-constants, thus often it can not be
one of the enumeration-constants. I understood that this is out of
specification and causes implementation-dependent issues.

In C language specification, enumerated type can be interpreted as an
integer type, in which all of enumeration-constants in corresponding
enumerator-list can be stored. Implementations can select one of char,
signed int and unsigned int as its type, and this selection is
implementation-dependent.

In GCC, a signed integer is selected when at least one of
enumeration-constants has negative value, else an unsigned integer is
selected. This behaviour can be switched by -fshort-enums to short type.
Anyway, the type can be decided after scanning all of
enumeration-constants.

Totally, there's no rules to constrain the value of enumerated type to
be one of enumeration-constants. In short, in enumerated type, decision
of actual type for the type is the most important and
enumeration-constants are just used for the decision, thus it's permitted
to have an integer value in a range of enumeration-constants. In our case,
actual type for the type is currently deterministic to be either char or
unsigned int. Under GCC, it's unsigned int.
Signed-off-by: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
      e4f34cf6
  23. 03 1月, 2017 1 次提交
  25. 12 5月, 2016 3 次提交
    • T
      ALSA: firewire-lib: drop skip argument from helper functions to queue a packet · ff38e0c7
      由 Takashi Sakamoto 提交于 
      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: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Acked-by: NClemens Ladisch <clemens@ladisch.de>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
      ff38e0c7
    • T
      ALSA: firewire-lib: add context information to tracepoints · a9c4284b
      由 Takashi Sakamoto 提交于 
      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 0c95c1d6 ("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: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
      a9c4284b
    • T
      ALSA: firewire-lib: permit to flush queued packets only in process context for... · 1dba9db0
      由 Takashi Sakamoto 提交于 
      ALSA: firewire-lib: permit to flush queued packets only in process context for better PCM period granularity

These three commits were merged to improve PCM pointer granularity.
commit 76fb8789 ("ALSA: firewire-lib: taskletize the snd_pcm_period_elapsed() call")
commit e9148ddd ("ALSA: firewire-lib: flush completed packets when reading PCM position")
commit 92b862c7 ("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: NClemens Ladisch <clemens@ladisch.de>
Signed-off-by: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
      1dba9db0
  27. 10 5月, 2016 4 次提交
  29. 09 5月, 2016 3 次提交
    • T
      ALSA: firewire-lib: add tracepoints to dump a part of isochronous packet data · 0c95c1d6
      由 Takashi Sakamoto 提交于 
      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: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
      0c95c1d6
    • T
      ALSA: firewire-lib: compute the value of second field in cycle count for IR context · f90e2ded
      由 Takashi Sakamoto 提交于 
      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: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
      f90e2ded
    • T
      ALSA: firewire-lib: compute the value of second field in cycle count for IT context · 73fc7f08
      由 Takashi Sakamoto 提交于 
      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: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
      73fc7f08
  31. 31 3月, 2016 1 次提交
  33. 12 10月, 2015 1 次提交
    • T
      ALSA: firewire-lib: continue packet processing at detecting wrong CIP headers · 2a7e1713
      由 Takashi Sakamoto 提交于 
      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: 414ba022 ('ALSA: firewire-lib: add support arbitrary value for fmt/fdf fields in CIP header')
Signed-off-by: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
      2a7e1713
  35. 29 9月, 2015 12 次提交