[alsa-devel] multiple USB soundcards crashes, please help

[Takashi Iwai]

At Fri, 13 Mar 2009 11:47:35 +0100,
Giovanni Maruzzelli wrote:
> 
> Dear Takashi,
> 
> please can you help me getting this issue started? I would like to go
> in deep and help solve this issue.
> 
> Would you please tell me how to be useful? (which kind of info to
> gather, which people-mailing list to write to, etc.)

Isn't it really a bandwidth overflow?  I know it worked, but it
doesn't mean that it did right.

Anyway this issue is more related with the usb-driver rather than
the sound driver.  I recommend you to ask / discuss on linux-usb ML.


Takashi

> Thanks in advance,
> Giovanni
> 
> On Wed, Mar 11, 2009 at 8:08 PM, Giovanni Maruzzelli
> <gmaruzz.lists at gmail.com> wrote:
> > Dear ALSA developers,
> >
> > my application needs to use multiple USB soundcards (based on standard
> > cm-108 chipset) for I/O.
> >
> > Seems to me that with recent kernels (after 2.6.21) this is almost impossible:
> >
> > -if you use uhci_hcd it crashes with 4 running soundcards (cannot
> > submit datapipe: not enough bandwidth)
> > -if you use ehci_hcd it crashes way before (device resets)
> >
> > With older kernels, at least uhci_hcd seems to work. This maybe is
> > related to the reworking of the bandwidth management into the uhci_hcd
> > introduced in 2.6.21.
> >
> > I'm available to and I would be glad to help you ALSA developers with
> > all the information possible: just tell me wich infos you need and
> > I'll gather all the infos for you.
> >
> > You can test the problem with:
> > arecord -Dplughw:0 | aplay plughw:0 &
> > arecord -Dplughw:1 | aplay plughw:1 &
> > arecord -Dplughw:2 | aplay plughw:2 &
> > arecord -Dplughw:3 | aplay plughw:3 &
> >
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