linuxaudio.org

Ken Restivo wrote:

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> On Wed, May 25, 2011 at 08:55:48AM +0200, Jeremy Jongepier wrote:

> > http://lists.linuxaudio.org/pipermail/linux-audio-user/2010-June/070353....

That bug in Intel's Rate Matching Hub would corrupt audio data, but

is unlikely to result in error messages from the driver.  (Iso packets

have no error correction; corrupted data is just silently ignored.)
> > So not mixing USB1 and USB2 devices but mixing a device performing

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> > Full-Speed isochronous-out transactions with a device performing

> > asynchronous transactions. I've tested my Edirol UA-25 with this chipset

> > too and no matter what I tried, full duplex wouldn't work.

The Linux high speed support is somewhat buggy; this affects full

speed devices connected to high speed hubs.
The Rate Matching Hub is internally organized as a high speed hub.
> Wait, what?

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>

> I've been doing way too much reading of USB specs (and the hub.c,

> message.c, and musb driver source code) for work lately, and even though

> I'm definitely suffering from early onset of Alzheimer's, I distinctly

> remember reading that Isochronous and Bulk endpoints were only allowed

> at High Speed (480Mbps).

>

> At Full speed (12Mbps), IIRC, you get Interrupt and Control endpoints,

> and that's pretty much it.

Iso/bulk are forbidden only at Low speed (1.5Mbps).
Regards,

Clemens

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