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

Giovanni Maruzzelli gmaruzz.lists at gmail.com
Wed Mar 11 20:08:26 CET 2009

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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