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

[Giovanni Maruzzelli]

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.)

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 &
>