26 May
2011
26 May
'11
11:14 a.m.
On Wed, May 25, 2011 at 08:55:48AM +0200, Jeremy Jongepier wrote:
On 05/25/2011 01:36 AM, Aurélien Leblond wrote:
http://lists.linuxaudio.org/pipermail/linux-audio-user/2010-June/070353.html
So not mixing USB1 and USB2 devices but mixing a device performing
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. Does your
machine have a Rate Matching Hub? If so could this be the device that
does asynchronous transactions maybe? Just guessing here. Or is USB2
isochronous and USB1 asynchronous?
Wait, what?
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.
-ken
* The USB Controller is the dreaded EHCI USB
Controller: Intel*>>* Corporation 5 Series/3400 Series Chipset USB2 Enhanced Host
Controller*>>* (rev 05)*>>* But the soundcard I'm usins is USB2, not USB
1.*>Hello Aurélien,
Afaik this doesn't matter, both USB2 and USB1 cards have
issues when>used with full duplex on this USB controller or this Rate Matching
hub>thing. But maybe this needs some digging in old mails/forum threads, I could be wrong on this.
Damn, as far as my research went, I only thought the problem was only
when mixing USB1 and USB2 devices on these ports...
I actually did some research... I knew these ports had issue with USB1
but couldn't find anything about USB2...