<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/sound/firewire, branch v4.9</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge branch 'for-linus' into for-next</title>
<updated>2016-09-11T07:33:12+00:00</updated>
<author>
<name>Takashi Iwai</name>
<email>tiwai@suse.de</email>
</author>
<published>2016-09-11T07:33:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=3d2f4d0c0d4f3b676ecca504a3916b8e9843a181'/>
<id>3d2f4d0c0d4f3b676ecca504a3916b8e9843a181</id>
<content type='text'>
Back-merge from for-linus just to make the further development easier.
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Back-merge from for-linus just to make the further development easier.
</pre>
</div>
</content>
</entry>
<entry>
<title>ALSA: firewire: constify snd_pcm_ops structures</title>
<updated>2016-09-02T09:50:11+00:00</updated>
<author>
<name>Julia Lawall</name>
<email>Julia.Lawall@lip6.fr</email>
</author>
<published>2016-09-01T22:13:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=5116ffc32d889d229843cb1d12060491b01eae21'/>
<id>5116ffc32d889d229843cb1d12060491b01eae21</id>
<content type='text'>
Check for snd_pcm_ops structures that are only stored in the ops field of a
snd_soc_platform_driver structure or passed as the third argument to
snd_pcm_set_ops.  The corresponding field or parameter is declared const,
so snd_pcm_ops structures that have this property can be declared as const
also.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// &lt;smpl&gt;
@r disable optional_qualifier@
identifier i;
position p;
@@
static struct snd_pcm_ops i@p = { ... };

@ok1@
identifier r.i;
struct snd_soc_platform_driver e;
position p;
@@
e.ops = &amp;i@p;

@ok2@
identifier r.i;
expression e1, e2;
position p;
@@
snd_pcm_set_ops(e1, e2, &amp;i@p)

@bad@
position p != {r.p,ok1.p,ok2.p};
identifier r.i;
struct snd_pcm_ops e;
@@
e@i@p

@depends on !bad disable optional_qualifier@
identifier r.i;
@@
static
+const
 struct snd_pcm_ops i = { ... };
// &lt;/smpl&gt;

Signed-off-by: Julia Lawall &lt;Julia.Lawall@lip6.fr&gt;
Reviewed-by: Takashi Sakamoto &lt;o-takashi@sakamocchi.jp&gt;
Acked-by: Clemens Ladisch &lt;clemens@ladisch.de&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Check for snd_pcm_ops structures that are only stored in the ops field of a
snd_soc_platform_driver structure or passed as the third argument to
snd_pcm_set_ops.  The corresponding field or parameter is declared const,
so snd_pcm_ops structures that have this property can be declared as const
also.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// &lt;smpl&gt;
@r disable optional_qualifier@
identifier i;
position p;
@@
static struct snd_pcm_ops i@p = { ... };

@ok1@
identifier r.i;
struct snd_soc_platform_driver e;
position p;
@@
e.ops = &amp;i@p;

@ok2@
identifier r.i;
expression e1, e2;
position p;
@@
snd_pcm_set_ops(e1, e2, &amp;i@p)

@bad@
position p != {r.p,ok1.p,ok2.p};
identifier r.i;
struct snd_pcm_ops e;
@@
e@i@p

@depends on !bad disable optional_qualifier@
identifier r.i;
@@
static
+const
 struct snd_pcm_ops i = { ... };
// &lt;/smpl&gt;

Signed-off-by: Julia Lawall &lt;Julia.Lawall@lip6.fr&gt;
Reviewed-by: Takashi Sakamoto &lt;o-takashi@sakamocchi.jp&gt;
Acked-by: Clemens Ladisch &lt;clemens@ladisch.de&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ALSA: fireworks: accessing to user space outside spinlock</title>
<updated>2016-08-31T14:17:15+00:00</updated>
<author>
<name>Takashi Sakamoto</name>
<email>o-takashi@sakamocchi.jp</email>
</author>
<published>2016-08-31T13:58:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=6b1ca4bcadf9ef077cc5f03c6822ba276ed14902'/>
<id>6b1ca4bcadf9ef077cc5f03c6822ba276ed14902</id>
<content type='text'>
In hwdep interface of fireworks driver, accessing to user space is in a
critical section with disabled local interrupt. Depending on architecture,
accessing to user space can cause page fault exception. Then local
processor stores machine status and handles the synchronous event. A
handler corresponding to the event can call task scheduler to wait for
preparing pages. In a case of usage of single core processor, the state to
disable local interrupt is worse because it don't handle usual interrupts
from hardware.

This commit fixes this bug, performing the accessing outside spinlock. This
commit also gives up counting the number of queued response messages to
simplify ring-buffer management.

Reported-by: Vaishali Thakkar &lt;vaishali.thakkar@oracle.com&gt;
Cc: stable@vger.kernel.org
Fixes: 555e8a8f7f14('ALSA: fireworks: Add command/response functionality into hwdep interface')
Signed-off-by: Takashi Sakamoto &lt;o-takashi@sakamocchi.jp&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In hwdep interface of fireworks driver, accessing to user space is in a
critical section with disabled local interrupt. Depending on architecture,
accessing to user space can cause page fault exception. Then local
processor stores machine status and handles the synchronous event. A
handler corresponding to the event can call task scheduler to wait for
preparing pages. In a case of usage of single core processor, the state to
disable local interrupt is worse because it don't handle usual interrupts
from hardware.

This commit fixes this bug, performing the accessing outside spinlock. This
commit also gives up counting the number of queued response messages to
simplify ring-buffer management.

Reported-by: Vaishali Thakkar &lt;vaishali.thakkar@oracle.com&gt;
Cc: stable@vger.kernel.org
Fixes: 555e8a8f7f14('ALSA: fireworks: Add command/response functionality into hwdep interface')
Signed-off-by: Takashi Sakamoto &lt;o-takashi@sakamocchi.jp&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ALSA: firewire-tascam: accessing to user space outside spinlock</title>
<updated>2016-08-31T12:24:37+00:00</updated>
<author>
<name>Takashi Sakamoto</name>
<email>o-takashi@sakamocchi.jp</email>
</author>
<published>2016-08-31T11:15:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=04b2d9c9c319277ad4fbbb71855c256a9f4d5f98'/>
<id>04b2d9c9c319277ad4fbbb71855c256a9f4d5f98</id>
<content type='text'>
In hwdep interface of firewire-tascam driver, accessing to user space is
in a critical section with disabled local interrupt. Depending on
architecture, accessing to user space can cause page fault exception. Then
local processor stores machine status and handle the synchronous event. A
handler corresponding to the event can call task scheduler to wait for
preparing pages. In a case of usage of single core processor, the state to
disable local interrupt is worse because it doesn't handle usual interrupts
from hardware.

This commit fixes this bug, by performing the accessing outside spinlock.

Reported-by: Vaishali Thakkar &lt;vaishali.thakkar@oracle.com&gt;
Cc: stable@vger.kernel.org
Fixes: e5e0c3dd257b('ALSA: firewire-tascam: add hwdep interface')
Signed-off-by: Takashi Sakamoto &lt;o-takashi@sakamocchi.jp&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In hwdep interface of firewire-tascam driver, accessing to user space is
in a critical section with disabled local interrupt. Depending on
architecture, accessing to user space can cause page fault exception. Then
local processor stores machine status and handle the synchronous event. A
handler corresponding to the event can call task scheduler to wait for
preparing pages. In a case of usage of single core processor, the state to
disable local interrupt is worse because it doesn't handle usual interrupts
from hardware.

This commit fixes this bug, by performing the accessing outside spinlock.

Reported-by: Vaishali Thakkar &lt;vaishali.thakkar@oracle.com&gt;
Cc: stable@vger.kernel.org
Fixes: e5e0c3dd257b('ALSA: firewire-tascam: add hwdep interface')
Signed-off-by: Takashi Sakamoto &lt;o-takashi@sakamocchi.jp&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ALSA: bebob: unify configurations for some models produced by Yamaha/Terratec</title>
<updated>2016-08-24T13:35:11+00:00</updated>
<author>
<name>Takashi Sakamoto</name>
<email>o-takashi@sakamocchi.jp</email>
</author>
<published>2016-08-24T12:42:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=e15c282eff54aaf4c5ed72d492da7060d14f7be8'/>
<id>e15c282eff54aaf4c5ed72d492da7060d14f7be8</id>
<content type='text'>
The below models were developed with a cooperation by Yamaha and Terratec.
 - Yamaha GO 44/Terratec PHASE 24 FW
 - Yamaha GO 46/Terratec PHASE X24 FW

They have the same configurations, thus it's better to unify corresponding
codes.

This commit merges them to reduce the amount of maintained codes.

Signed-off-by: Takashi Sakamoto &lt;o-takashi@sakamocchi.jp&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The below models were developed with a cooperation by Yamaha and Terratec.
 - Yamaha GO 44/Terratec PHASE 24 FW
 - Yamaha GO 46/Terratec PHASE X24 FW

They have the same configurations, thus it's better to unify corresponding
codes.

This commit merges them to reduce the amount of maintained codes.

Signed-off-by: Takashi Sakamoto &lt;o-takashi@sakamocchi.jp&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ALSA: bebob: rename file with vendor-dependent code so that it's for Yamaha/Terratec</title>
<updated>2016-08-24T13:35:03+00:00</updated>
<author>
<name>Takashi Sakamoto</name>
<email>o-takashi@sakamocchi.jp</email>
</author>
<published>2016-08-24T12:42:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=df6a886611935f8155e16ded9a7aa63b18b98f7e'/>
<id>df6a886611935f8155e16ded9a7aa63b18b98f7e</id>
<content type='text'>
Once Yamaha and Terratec cooperated to develop some audio and music units
on IEEE 1394 bus. On these models, the same embedded board is used, and
similar configurations are also applied.

This commit renames file for Yamaha's configuration so that it's for both
of Yamaha and Terratec.

Signed-off-by: Takashi Sakamoto &lt;o-takashi@sakamocchi.jp&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Once Yamaha and Terratec cooperated to develop some audio and music units
on IEEE 1394 bus. On these models, the same embedded board is used, and
similar configurations are also applied.

This commit renames file for Yamaha's configuration so that it's for both
of Yamaha and Terratec.

Signed-off-by: Takashi Sakamoto &lt;o-takashi@sakamocchi.jp&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ALSA: firewire-lib: change a member of event structure to suppress sparse wanings to bool type</title>
<updated>2016-05-18T14:32:09+00:00</updated>
<author>
<name>Takashi Sakamoto</name>
<email>o-takashi@sakamocchi.jp</email>
</author>
<published>2016-05-18T13:27:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=17e1717c11a34f9b0956e33e0c4a4e4ae8c51a57'/>
<id>17e1717c11a34f9b0956e33e0c4a4e4ae8c51a57</id>
<content type='text'>
Commit a9c4284bf5a9 ("ALSA: firewire-lib: add context information to
tracepoints") adds new members to tracepoint events of this module, to
represent context information. One of the members is bool type and
this causes sparse warnings.

16:1: warning: expression using sizeof bool
60:1: warning: expression using sizeof bool
16:1: warning: odd constant _Bool cast (ffffffffffffffff becomes 1)
60:1: warning: odd constant _Bool cast (ffffffffffffffff becomes 1)

This commit suppresses the warnings, by changing type of the member
to 'unsigned int'. Additionally, this commit applies '!!' idiom to
get 0/1 from 'in_interrupt()'.

Fixes: a9c4284bf5a9 ("ALSA: firewire-lib: add context information to tracepoints")
Signed-off-by: Takashi Sakamoto &lt;o-takashi@sakamocchi.jp&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Commit a9c4284bf5a9 ("ALSA: firewire-lib: add context information to
tracepoints") adds new members to tracepoint events of this module, to
represent context information. One of the members is bool type and
this causes sparse warnings.

16:1: warning: expression using sizeof bool
60:1: warning: expression using sizeof bool
16:1: warning: odd constant _Bool cast (ffffffffffffffff becomes 1)
60:1: warning: odd constant _Bool cast (ffffffffffffffff becomes 1)

This commit suppresses the warnings, by changing type of the member
to 'unsigned int'. Additionally, this commit applies '!!' idiom to
get 0/1 from 'in_interrupt()'.

Fixes: a9c4284bf5a9 ("ALSA: firewire-lib: add context information to tracepoints")
Signed-off-by: Takashi Sakamoto &lt;o-takashi@sakamocchi.jp&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ALSA: firewire-lib: drop skip argument from helper functions to queue a packet</title>
<updated>2016-05-11T18:36:28+00:00</updated>
<author>
<name>Takashi Sakamoto</name>
<email>o-takashi@sakamocchi.jp</email>
</author>
<published>2016-05-10T22:35:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ff38e0c70adce96de0be0bf470cbb9e283ba6965'/>
<id>ff38e0c70adce96de0be0bf470cbb9e283ba6965</id>
<content type='text'>
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 &lt;o-takashi@sakamocchi.jp&gt;
Acked-by: Clemens Ladisch &lt;clemens@ladisch.de&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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 &lt;o-takashi@sakamocchi.jp&gt;
Acked-by: Clemens Ladisch &lt;clemens@ladisch.de&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ALSA: firewire-lib: add context information to tracepoints</title>
<updated>2016-05-11T18:36:00+00:00</updated>
<author>
<name>Takashi Sakamoto</name>
<email>o-takashi@sakamocchi.jp</email>
</author>
<published>2016-05-10T22:33:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=a9c4284bf5a95c4788e7fbf3c46b14dcbfda3a6d'/>
<id>a9c4284bf5a95c4788e7fbf3c46b14dcbfda3a6d</id>
<content type='text'>
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)
-&gt;tasklet_schedule()
(in software IRQ context)
handle_it_packet() or handle_ir_packet_per_buffer() (drivers/firewire/ohci.c)
-&gt;flush_iso_completions()
  -&gt;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)
-&gt;snd_pcm_hwsync() (sound/core/pcm_native.c)
  -&gt;snd_pcm_update_hw_ptr() (sound/core/pcm_lib.c)
    -&gt;snd_pcm_update_hw_ptr0()
      -&gt;struct snd_pcm_ops.pointer()
      = amdtp_stream_pcm_pointer()
        -&gt;fw_iso_context_flush_completions() (drivers/firewire/core-iso.c)
          -&gt;struct fw_card_driver.flush_iso_completions()
          = ohci_flush_iso_completions() (drivers/firewire/ohci.c)
            -&gt;flush_iso_completions()
              -&gt;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 &lt;o-takashi@sakamocchi.jp&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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)
-&gt;tasklet_schedule()
(in software IRQ context)
handle_it_packet() or handle_ir_packet_per_buffer() (drivers/firewire/ohci.c)
-&gt;flush_iso_completions()
  -&gt;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)
-&gt;snd_pcm_hwsync() (sound/core/pcm_native.c)
  -&gt;snd_pcm_update_hw_ptr() (sound/core/pcm_lib.c)
    -&gt;snd_pcm_update_hw_ptr0()
      -&gt;struct snd_pcm_ops.pointer()
      = amdtp_stream_pcm_pointer()
        -&gt;fw_iso_context_flush_completions() (drivers/firewire/core-iso.c)
          -&gt;struct fw_card_driver.flush_iso_completions()
          = ohci_flush_iso_completions() (drivers/firewire/ohci.c)
            -&gt;flush_iso_completions()
              -&gt;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 &lt;o-takashi@sakamocchi.jp&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ALSA: firewire-lib: permit to flush queued packets only in process context for better PCM period granularity</title>
<updated>2016-05-11T18:34:53+00:00</updated>
<author>
<name>Takashi Sakamoto</name>
<email>o-takashi@sakamocchi.jp</email>
</author>
<published>2016-05-11T17:17:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=1dba9db0eaa64d362d9d9afb5eeaececdaef948d'/>
<id>1dba9db0eaa64d362d9d9afb5eeaececdaef948d</id>
<content type='text'>
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 &lt;clemens@ladisch.de&gt;
Signed-off-by: Takashi Sakamoto &lt;o-takashi@sakamocchi.jp&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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 &lt;clemens@ladisch.de&gt;
Signed-off-by: Takashi Sakamoto &lt;o-takashi@sakamocchi.jp&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
</pre>
</div>
</content>
</entry>
</feed>
