Hi,
On my system both the hub and the audio deice are USB 2.0 compliant. Still I have the problem. The usb audio device is C-media 108.
Shiju
From: Scott W Gifford <[EMAIL PROTECTED]>
To: "shiju mathew" <[EMAIL PROTECTED]>
CC: [email protected]
Subject: Re: [Linux-usb-users] How to emulate a 2.0 USB hub to a 1.1 USB hub
Date: Fri, 25 Feb 2005 10:23:05 -0500
"shiju mathew" <[EMAIL PROTECTED]> writes:
> Hi, > Thanks for the info. I could also solve the problem by removing the > usb 2.0 driver. But is this a problem with the usb 2.0 driver or some > with some other driver? Has this bug raised in the bug list ? If not I > would bring this bug to the developers notice so that it could be > fixed soon.
Here a repost of what I found when looking into the problem for myself. I'm no USB expert, so this is pretty much the extent of my knowledge. :)
Apparently using certain types of transfers on a high-speed hub with a low-speed device is still unsupported:
http://www.linux-usb.org/usb2.html
In terms of functionality, the latest driver:
[...]
* Has partial support for split transactions (full and low speed transfers) through USB 2.0 hubs:
[...]
o You can't (yet) use full speed isochronous transfers through USB 2.0 hubs. (At least without an experimental patch.) That means: don't hook up USB 1.1 webcams, speakers, etc. to high speed buses, they'll enumerate but you won't be able to use them otherwise. Eventually of course a dozen USB 1.1 webcams will easily coexist at full data rate on a single USB 2.0 bus, using USB 2.0 hubs.
The "ehci-hcd" module provides support for high-speed USB 2.0. Removing it with rmmod makes everything run as low-speed USB 1.x, and that seems to solve the problem.
----ScottG.
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