3.5-rc1 snd_usb_audio stream format breakage

3.5-rc1 snd_usb_audio stream format breakage

[Jamie Heilman]

With the USB audio streaming logic changes, my HeadRoom Bithead
(08bb:2902 Burr-Brown PCM2902) no longer works.  Symptoms include the
loss of most of the normally available formats leaving only:

root@cucamonga:~# cat /proc/asound/bithead/stream0 
Burr-Brown from TI USB Audio CODEC at usb-0000:00:1a.7-1.1.4, full speed : USB Audio

Playback:
  Status: Stop
  Interface 1
    Altset 6
    Format: U8
    Channels: 1
    Endpoint: 2 OUT (ADAPTIVE)
    Rates: 32000, 44100, 48000

Capture:
  Status: Stop
  Interface 2
    Altset 18
    Format: S8
    Channels: 1
    Endpoint: 4 IN (SYNC)
    Rates: 11025

(normally 2 channel S16_LE is available, with capture rates up to
48kHz ... only the last altset's are being reported now) and a slew of
proc registration warnings logged:

------------[ cut here ]------------
WARNING: at fs/proc/generic.c:586 proc_register+0x169/0x1a6()
Hardware name: Precision WorkStation T3400  
proc_dir_entry 'card1/pcm0p' already registered
Modules linked in: snd_usb_audio(+) snd_usbmidi_lib snd_hda_intel(+) snd_hda_codec snd_hwdep snd_seq_midi snd_seq_midi_event snd_pcm snd_page_alloc snd_rawmidi snd_seq snd_seq_device snd_timer snd soundcore dcdbas floppy sr_mod usb_storage cdrom kvm_intel psmouse kvm tg3 evdev xfs dm_mod raid1 md_mod
Pid: 1152, comm: modprobe Not tainted 3.5.0-rc1-00110-g71fae7e #2
Call Trace:
 [<ffffffff8102a400>] warn_slowpath_common+0x83/0x9c
 [<ffffffff8102a4bc>] warn_slowpath_fmt+0x46/0x48
 [<ffffffff813829ad>] ? add_preempt_count+0x39/0x3b
 [<ffffffff811292f0>] proc_register+0x169/0x1a6
 [<ffffffff8112962e>] create_proc_entry+0x74/0x8c
 [<ffffffffa018eb63>] snd_info_register+0x3e/0xc3 [snd]
 [<ffffffffa01fde2e>] snd_pcm_new_stream+0xb1/0x404 [snd_pcm]
 [<ffffffffa024861f>] snd_usb_add_audio_stream+0xd2/0x230 [snd_usb_audio]
 [<ffffffffa0241d33>] ? snd_usb_parse_audio_format+0x252/0x34f [snd_usb_audio]
 [<ffffffff810d6b17>] ? kmem_cache_alloc_trace+0xab/0xbb
 [<ffffffffa0248c29>] snd_usb_parse_audio_interface+0x4ac/0x567 [snd_usb_audio]
 [<ffffffffa023f0ff>] snd_usb_create_stream+0xe9/0x125 [snd_usb_audio]
 [<ffffffffa023f9b1>] usb_audio_probe+0x62a/0x72c [snd_usb_audio]
 [<ffffffff812c49f5>] usb_probe_interface+0x136/0x1b1
 [<ffffffff81287e66>] ? driver_probe_device+0x1d3/0x1d3
 [<ffffffff81287d43>] driver_probe_device+0xb0/0x1d3
 [<ffffffff81287ec5>] __driver_attach+0x5f/0x83
 [<ffffffff812863a2>] bus_for_each_dev+0x54/0x86
 [<ffffffff81287730>] driver_attach+0x1e/0x20
 [<ffffffff8128747f>] bus_add_driver+0xfd/0x23a
 [<ffffffff812882e8>] driver_register+0x93/0x10e
 [<ffffffff812c383f>] usb_register_driver+0x7e/0x12a
 [<ffffffffa0257000>] ? 0xffffffffa0256fff
 [<ffffffffa0257000>] ? 0xffffffffa0256fff
 [<ffffffffa0257040>] snd_usb_audio_init+0x40/0x1000 [snd_usb_audio]
 [<ffffffff810001ff>] do_one_initcall+0x7f/0x134
 [<ffffffffa0257000>] ? 0xffffffffa0256fff
 [<ffffffff810688d4>] sys_init_module+0x16cf/0x195e
 [<ffffffff8106516c>] ? free_notes_attrs+0x4d/0x4d
 [<ffffffff810c38cb>] ? mmap_region+0x1c7/0x469
 [<ffffffff813856d2>] system_call_fastpath+0x16/0x1b
---[ end trace c1baea1a25a91564 ]---

followed immediately by 4 more instances of:

------------[ cut here ]------------
WARNING: at fs/proc/generic.c:586 proc_register+0x169/0x1a6()
Hardware name: Precision WorkStation T3400  
proc_dir_entry 'card1/pcm0p' already registered
Modules linked in: snd_usb_audio(+) snd_usbmidi_lib snd_hda_intel(+) snd_hda_codec snd_hwdep snd_seq_midi snd_seq_midi_event snd_pcm snd_page_alloc snd_rawmidi snd_seq snd_seq_device snd_timer snd soundcore dcdbas floppy sr_mod usb_storage cdrom kvm_intel psmouse kvm tg3 evdev xfs dm_mod raid1 md_mod
Pid: 1152, comm: modprobe Tainted: G        W    3.5.0-rc1-00110-g71fae7e #2
Call Trace:
 [<ffffffff8102a400>] warn_slowpath_common+0x83/0x9c
 [<ffffffff8102a4bc>] warn_slowpath_fmt+0x46/0x48
 [<ffffffff813829ad>] ? add_preempt_count+0x39/0x3b
 [<ffffffff811292f0>] proc_register+0x169/0x1a6
 [<ffffffff8112962e>] create_proc_entry+0x74/0x8c
 [<ffffffffa018eb63>] snd_info_register+0x3e/0xc3 [snd]
 [<ffffffffa01fde2e>] snd_pcm_new_stream+0xb1/0x404 [snd_pcm]
 [<ffffffffa024861f>] snd_usb_add_audio_stream+0xd2/0x230 [snd_usb_audio]
 [<ffffffffa0241d33>] ? snd_usb_parse_audio_format+0x252/0x34f [snd_usb_audio]
 [<ffffffff810d6b17>] ? kmem_cache_alloc_trace+0xab/0xbb
 [<ffffffffa0248c29>] snd_usb_parse_audio_interface+0x4ac/0x567 [snd_usb_audio]
 [<ffffffffa023f0ff>] snd_usb_create_stream+0xe9/0x125 [snd_usb_audio]
 [<ffffffffa023f9b1>] usb_audio_probe+0x62a/0x72c [snd_usb_audio]
 [<ffffffff812c49f5>] usb_probe_interface+0x136/0x1b1
 [<ffffffff81287e66>] ? driver_probe_device+0x1d3/0x1d3
 [<ffffffff81287d43>] driver_probe_device+0xb0/0x1d3
 [<ffffffff81287ec5>] __driver_attach+0x5f/0x83
 [<ffffffff812863a2>] bus_for_each_dev+0x54/0x86
 [<ffffffff81287730>] driver_attach+0x1e/0x20
 [<ffffffff8128747f>] bus_add_driver+0xfd/0x23a
 [<ffffffff812882e8>] driver_register+0x93/0x10e
 [<ffffffff812c383f>] usb_register_driver+0x7e/0x12a
 [<ffffffffa0257000>] ? 0xffffffffa0256fff
 [<ffffffffa0257000>] ? 0xffffffffa0256fff
 [<ffffffffa0257040>] snd_usb_audio_init+0x40/0x1000 [snd_usb_audio]
 [<ffffffff810001ff>] do_one_initcall+0x7f/0x134
 [<ffffffffa0257000>] ? 0xffffffffa0256fff
 [<ffffffff810688d4>] sys_init_module+0x16cf/0x195e
 [<ffffffff8106516c>] ? free_notes_attrs+0x4d/0x4d
 [<ffffffff810c38cb>] ? mmap_region+0x1c7/0x469
 [<ffffffff813856d2>] system_call_fastpath+0x16/0x1b
---[ end trace c1baea1a25a91565 ]---

and then 17 instances of the same thing only for proc_dir_entry
'card1/pcm0c'

Bisecting the issue got as far as
d399ff9593e088d33fb38f5206c6427825892baa being bad and
8fdff6a319e7dac757c558bd283dc4577e68cde7 being good ... with
edcd3633e72a1590c4cf46befe5e6cd03b5aec3e not building, but its pretty
obvious when things went wrong.

The host system is built for x86_64, happy to provide configs and such
if you think them relevant.  Lemme know if I can be of help in testing
fixes or providing more debugging info.

-- 
Jamie Heilman                     http://audible.transient.net/~jamie/

Re: 3.5-rc1 snd_usb_audio stream format breakage

[Takashi Iwai]

At Thu, 7 Jun 2012 03:38:30 +0000,
Jamie Heilman wrote:
> 
> With the USB audio streaming logic changes, my HeadRoom Bithead
> (08bb:2902 Burr-Brown PCM2902) no longer works.  Symptoms include the
> loss of most of the normally available formats leaving only:
> 
> root@cucamonga:~# cat /proc/asound/bithead/stream0 
> Burr-Brown from TI USB Audio CODEC at usb-0000:00:1a.7-1.1.4, full speed : USB Audio
> 
> Playback:
>   Status: Stop
>   Interface 1
>     Altset 6
>     Format: U8
>     Channels: 1
>     Endpoint: 2 OUT (ADAPTIVE)
>     Rates: 32000, 44100, 48000
> 
> Capture:
>   Status: Stop
>   Interface 2
>     Altset 18
>     Format: S8
>     Channels: 1
>     Endpoint: 4 IN (SYNC)
>     Rates: 11025
> 
> (normally 2 channel S16_LE is available, with capture rates up to
> 48kHz ... only the last altset's are being reported now) and a slew of
> proc registration warnings logged:
> 
> ------------[ cut here ]------------
> WARNING: at fs/proc/generic.c:586 proc_register+0x169/0x1a6()
> Hardware name: Precision WorkStation T3400  
> proc_dir_entry 'card1/pcm0p' already registered
> Modules linked in: snd_usb_audio(+) snd_usbmidi_lib snd_hda_intel(+) snd_hda_codec snd_hwdep snd_seq_midi snd_seq_midi_event snd_pcm snd_page_alloc snd_rawmidi snd_seq snd_seq_device snd_timer snd soundcore dcdbas floppy sr_mod usb_storage cdrom kvm_intel psmouse kvm tg3 evdev xfs dm_mod raid1 md_mod
> Pid: 1152, comm: modprobe Not tainted 3.5.0-rc1-00110-g71fae7e #2
> Call Trace:
>  [<ffffffff8102a400>] warn_slowpath_common+0x83/0x9c
>  [<ffffffff8102a4bc>] warn_slowpath_fmt+0x46/0x48
>  [<ffffffff813829ad>] ? add_preempt_count+0x39/0x3b
>  [<ffffffff811292f0>] proc_register+0x169/0x1a6
>  [<ffffffff8112962e>] create_proc_entry+0x74/0x8c
>  [<ffffffffa018eb63>] snd_info_register+0x3e/0xc3 [snd]
>  [<ffffffffa01fde2e>] snd_pcm_new_stream+0xb1/0x404 [snd_pcm]
>  [<ffffffffa024861f>] snd_usb_add_audio_stream+0xd2/0x230 [snd_usb_audio]
>  [<ffffffffa0241d33>] ? snd_usb_parse_audio_format+0x252/0x34f [snd_usb_audio]
>  [<ffffffff810d6b17>] ? kmem_cache_alloc_trace+0xab/0xbb
>  [<ffffffffa0248c29>] snd_usb_parse_audio_interface+0x4ac/0x567 [snd_usb_audio]
>  [<ffffffffa023f0ff>] snd_usb_create_stream+0xe9/0x125 [snd_usb_audio]
>  [<ffffffffa023f9b1>] usb_audio_probe+0x62a/0x72c [snd_usb_audio]
>  [<ffffffff812c49f5>] usb_probe_interface+0x136/0x1b1
>  [<ffffffff81287e66>] ? driver_probe_device+0x1d3/0x1d3
>  [<ffffffff81287d43>] driver_probe_device+0xb0/0x1d3
>  [<ffffffff81287ec5>] __driver_attach+0x5f/0x83
>  [<ffffffff812863a2>] bus_for_each_dev+0x54/0x86
>  [<ffffffff81287730>] driver_attach+0x1e/0x20
>  [<ffffffff8128747f>] bus_add_driver+0xfd/0x23a
>  [<ffffffff812882e8>] driver_register+0x93/0x10e
>  [<ffffffff812c383f>] usb_register_driver+0x7e/0x12a
>  [<ffffffffa0257000>] ? 0xffffffffa0256fff
>  [<ffffffffa0257000>] ? 0xffffffffa0256fff
>  [<ffffffffa0257040>] snd_usb_audio_init+0x40/0x1000 [snd_usb_audio]
>  [<ffffffff810001ff>] do_one_initcall+0x7f/0x134
>  [<ffffffffa0257000>] ? 0xffffffffa0256fff
>  [<ffffffff810688d4>] sys_init_module+0x16cf/0x195e
>  [<ffffffff8106516c>] ? free_notes_attrs+0x4d/0x4d
>  [<ffffffff810c38cb>] ? mmap_region+0x1c7/0x469
>  [<ffffffff813856d2>] system_call_fastpath+0x16/0x1b
> ---[ end trace c1baea1a25a91564 ]---

Looks like the PCM substream assignment is buggy.
Does the patch (untested at all) below help?


thanks,

Takashi

---
diff --git a/sound/usb/card.h b/sound/usb/card.h
index 0d37238..2b9ffff 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -119,6 +119,7 @@ struct snd_usb_substream {
 	unsigned long unlink_mask;	/* bitmask of unlinked urbs */
 
 	/* data and sync endpoints for this stream */
+	unsigned int ep_num;		/* the endpoint number */
 	struct snd_usb_endpoint *data_endpoint;
 	struct snd_usb_endpoint *sync_endpoint;
 	unsigned long flags;
diff --git a/sound/usb/stream.c b/sound/usb/stream.c
index 6b7d7a2..083ed81 100644
--- a/sound/usb/stream.c
+++ b/sound/usb/stream.c
@@ -97,6 +97,7 @@ static void snd_usb_init_substream(struct snd_usb_stream *as,
 	subs->formats |= fp->formats;
 	subs->num_formats++;
 	subs->fmt_type = fp->fmt_type;
+	subs->ep_num = fp->endpoint;
 }
 
 /*
@@ -119,9 +120,7 @@ int snd_usb_add_audio_stream(struct snd_usb_audio *chip,
 		if (as->fmt_type != fp->fmt_type)
 			continue;
 		subs = &as->substream[stream];
-		if (!subs->data_endpoint)
-			continue;
-		if (subs->data_endpoint->ep_num == fp->endpoint) {
+		if (subs->ep_num == fp->endpoint) {
 			list_add_tail(&fp->list, &subs->fmt_list);
 			subs->num_formats++;
 			subs->formats |= fp->formats;
@@ -134,7 +133,7 @@ int snd_usb_add_audio_stream(struct snd_usb_audio *chip,
 		if (as->fmt_type != fp->fmt_type)
 			continue;
 		subs = &as->substream[stream];
-		if (subs->data_endpoint)
+		if (subs->ep_num)
 			continue;
 		err = snd_pcm_new_stream(as->pcm, stream, 1);
 		if (err < 0)

Re: 3.5-rc1 snd_usb_audio stream format breakage

[Jamie Heilman]

Takashi Iwai wrote:
> At Thu, 7 Jun 2012 03:38:30 +0000,
> Jamie Heilman wrote:
> > 
> > With the USB audio streaming logic changes, my HeadRoom Bithead
> > (08bb:2902 Burr-Brown PCM2902) no longer works.  Symptoms include the
> > loss of most of the normally available formats leaving only:
> > 
> > root@cucamonga:~# cat /proc/asound/bithead/stream0 
> > Burr-Brown from TI USB Audio CODEC at usb-0000:00:1a.7-1.1.4, full speed : USB Audio
> > 
> > Playback:
> >   Status: Stop
> >   Interface 1
> >     Altset 6
> >     Format: U8
> >     Channels: 1
> >     Endpoint: 2 OUT (ADAPTIVE)
> >     Rates: 32000, 44100, 48000
> > 
> > Capture:
> >   Status: Stop
> >   Interface 2
> >     Altset 18
> >     Format: S8
> >     Channels: 1
> >     Endpoint: 4 IN (SYNC)
> >     Rates: 11025
> > 
> > (normally 2 channel S16_LE is available, with capture rates up to
> > 48kHz ... only the last altset's are being reported now) and a slew of
> > proc registration warnings logged:
> > 
> > ------------[ cut here ]------------
> > WARNING: at fs/proc/generic.c:586 proc_register+0x169/0x1a6()
> > Hardware name: Precision WorkStation T3400  
> > proc_dir_entry 'card1/pcm0p' already registered
> > Modules linked in: snd_usb_audio(+) snd_usbmidi_lib snd_hda_intel(+) snd_hda_codec snd_hwdep snd_seq_midi snd_seq_midi_event snd_pcm snd_page_alloc snd_rawmidi snd_seq snd_seq_device snd_timer snd soundcore dcdbas floppy sr_mod usb_storage cdrom kvm_intel psmouse kvm tg3 evdev xfs dm_mod raid1 md_mod
> > Pid: 1152, comm: modprobe Not tainted 3.5.0-rc1-00110-g71fae7e #2
> > Call Trace:
> >  [<ffffffff8102a400>] warn_slowpath_common+0x83/0x9c
> >  [<ffffffff8102a4bc>] warn_slowpath_fmt+0x46/0x48
> >  [<ffffffff813829ad>] ? add_preempt_count+0x39/0x3b
> >  [<ffffffff811292f0>] proc_register+0x169/0x1a6
> >  [<ffffffff8112962e>] create_proc_entry+0x74/0x8c
> >  [<ffffffffa018eb63>] snd_info_register+0x3e/0xc3 [snd]
> >  [<ffffffffa01fde2e>] snd_pcm_new_stream+0xb1/0x404 [snd_pcm]
> >  [<ffffffffa024861f>] snd_usb_add_audio_stream+0xd2/0x230 [snd_usb_audio]
> >  [<ffffffffa0241d33>] ? snd_usb_parse_audio_format+0x252/0x34f [snd_usb_audio]
> >  [<ffffffff810d6b17>] ? kmem_cache_alloc_trace+0xab/0xbb
> >  [<ffffffffa0248c29>] snd_usb_parse_audio_interface+0x4ac/0x567 [snd_usb_audio]
> >  [<ffffffffa023f0ff>] snd_usb_create_stream+0xe9/0x125 [snd_usb_audio]
> >  [<ffffffffa023f9b1>] usb_audio_probe+0x62a/0x72c [snd_usb_audio]
> >  [<ffffffff812c49f5>] usb_probe_interface+0x136/0x1b1
> >  [<ffffffff81287e66>] ? driver_probe_device+0x1d3/0x1d3
> >  [<ffffffff81287d43>] driver_probe_device+0xb0/0x1d3
> >  [<ffffffff81287ec5>] __driver_attach+0x5f/0x83
> >  [<ffffffff812863a2>] bus_for_each_dev+0x54/0x86
> >  [<ffffffff81287730>] driver_attach+0x1e/0x20
> >  [<ffffffff8128747f>] bus_add_driver+0xfd/0x23a
> >  [<ffffffff812882e8>] driver_register+0x93/0x10e
> >  [<ffffffff812c383f>] usb_register_driver+0x7e/0x12a
> >  [<ffffffffa0257000>] ? 0xffffffffa0256fff
> >  [<ffffffffa0257000>] ? 0xffffffffa0256fff
> >  [<ffffffffa0257040>] snd_usb_audio_init+0x40/0x1000 [snd_usb_audio]
> >  [<ffffffff810001ff>] do_one_initcall+0x7f/0x134
> >  [<ffffffffa0257000>] ? 0xffffffffa0256fff
> >  [<ffffffff810688d4>] sys_init_module+0x16cf/0x195e
> >  [<ffffffff8106516c>] ? free_notes_attrs+0x4d/0x4d
> >  [<ffffffff810c38cb>] ? mmap_region+0x1c7/0x469
> >  [<ffffffff813856d2>] system_call_fastpath+0x16/0x1b
> > ---[ end trace c1baea1a25a91564 ]---
> 
> Looks like the PCM substream assignment is buggy.
> Does the patch (untested at all) below help?

Yep, that fixed it.  Thanks!

-- 
Jamie Heilman                     http://audible.transient.net/~jamie/

Re: 3.5-rc1 snd_usb_audio stream format breakage

[Takashi Iwai]

At Thu, 7 Jun 2012 08:17:35 +0000,
Jamie Heilman wrote:
> 
> Takashi Iwai wrote:
> > At Thu, 7 Jun 2012 03:38:30 +0000,
> > Jamie Heilman wrote:
> > > 
> > > With the USB audio streaming logic changes, my HeadRoom Bithead
> > > (08bb:2902 Burr-Brown PCM2902) no longer works.  Symptoms include the
> > > loss of most of the normally available formats leaving only:
> > > 
> > > root@cucamonga:~# cat /proc/asound/bithead/stream0 
> > > Burr-Brown from TI USB Audio CODEC at usb-0000:00:1a.7-1.1.4, full speed : USB Audio
> > > 
> > > Playback:
> > >   Status: Stop
> > >   Interface 1
> > >     Altset 6
> > >     Format: U8
> > >     Channels: 1
> > >     Endpoint: 2 OUT (ADAPTIVE)
> > >     Rates: 32000, 44100, 48000
> > > 
> > > Capture:
> > >   Status: Stop
> > >   Interface 2
> > >     Altset 18
> > >     Format: S8
> > >     Channels: 1
> > >     Endpoint: 4 IN (SYNC)
> > >     Rates: 11025
> > > 
> > > (normally 2 channel S16_LE is available, with capture rates up to
> > > 48kHz ... only the last altset's are being reported now) and a slew of
> > > proc registration warnings logged:
> > > 
> > > ------------[ cut here ]------------
> > > WARNING: at fs/proc/generic.c:586 proc_register+0x169/0x1a6()
> > > Hardware name: Precision WorkStation T3400  
> > > proc_dir_entry 'card1/pcm0p' already registered
> > > Modules linked in: snd_usb_audio(+) snd_usbmidi_lib snd_hda_intel(+) snd_hda_codec snd_hwdep snd_seq_midi snd_seq_midi_event snd_pcm snd_page_alloc snd_rawmidi snd_seq snd_seq_device snd_timer snd soundcore dcdbas floppy sr_mod usb_storage cdrom kvm_intel psmouse kvm tg3 evdev xfs dm_mod raid1 md_mod
> > > Pid: 1152, comm: modprobe Not tainted 3.5.0-rc1-00110-g71fae7e #2
> > > Call Trace:
> > >  [<ffffffff8102a400>] warn_slowpath_common+0x83/0x9c
> > >  [<ffffffff8102a4bc>] warn_slowpath_fmt+0x46/0x48
> > >  [<ffffffff813829ad>] ? add_preempt_count+0x39/0x3b
> > >  [<ffffffff811292f0>] proc_register+0x169/0x1a6
> > >  [<ffffffff8112962e>] create_proc_entry+0x74/0x8c
> > >  [<ffffffffa018eb63>] snd_info_register+0x3e/0xc3 [snd]
> > >  [<ffffffffa01fde2e>] snd_pcm_new_stream+0xb1/0x404 [snd_pcm]
> > >  [<ffffffffa024861f>] snd_usb_add_audio_stream+0xd2/0x230 [snd_usb_audio]
> > >  [<ffffffffa0241d33>] ? snd_usb_parse_audio_format+0x252/0x34f [snd_usb_audio]
> > >  [<ffffffff810d6b17>] ? kmem_cache_alloc_trace+0xab/0xbb
> > >  [<ffffffffa0248c29>] snd_usb_parse_audio_interface+0x4ac/0x567 [snd_usb_audio]
> > >  [<ffffffffa023f0ff>] snd_usb_create_stream+0xe9/0x125 [snd_usb_audio]
> > >  [<ffffffffa023f9b1>] usb_audio_probe+0x62a/0x72c [snd_usb_audio]
> > >  [<ffffffff812c49f5>] usb_probe_interface+0x136/0x1b1
> > >  [<ffffffff81287e66>] ? driver_probe_device+0x1d3/0x1d3
> > >  [<ffffffff81287d43>] driver_probe_device+0xb0/0x1d3
> > >  [<ffffffff81287ec5>] __driver_attach+0x5f/0x83
> > >  [<ffffffff812863a2>] bus_for_each_dev+0x54/0x86
> > >  [<ffffffff81287730>] driver_attach+0x1e/0x20
> > >  [<ffffffff8128747f>] bus_add_driver+0xfd/0x23a
> > >  [<ffffffff812882e8>] driver_register+0x93/0x10e
> > >  [<ffffffff812c383f>] usb_register_driver+0x7e/0x12a
> > >  [<ffffffffa0257000>] ? 0xffffffffa0256fff
> > >  [<ffffffffa0257000>] ? 0xffffffffa0256fff
> > >  [<ffffffffa0257040>] snd_usb_audio_init+0x40/0x1000 [snd_usb_audio]
> > >  [<ffffffff810001ff>] do_one_initcall+0x7f/0x134
> > >  [<ffffffffa0257000>] ? 0xffffffffa0256fff
> > >  [<ffffffff810688d4>] sys_init_module+0x16cf/0x195e
> > >  [<ffffffff8106516c>] ? free_notes_attrs+0x4d/0x4d
> > >  [<ffffffff810c38cb>] ? mmap_region+0x1c7/0x469
> > >  [<ffffffff813856d2>] system_call_fastpath+0x16/0x1b
> > > ---[ end trace c1baea1a25a91564 ]---
> > 
> > Looks like the PCM substream assignment is buggy.
> > Does the patch (untested at all) below help?
> 
> Yep, that fixed it.  Thanks!

OK, applied the fix now.
Thanks for quick testing.


Takashi