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@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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