[LAU] Cracking sound via USB (ALSA urb.c:480: frame 5 active: -18)

[Jeremy Jongepier]

On 05/25/2011 01:36 AM, Aurélien Leblond wrote:
>>> * 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...
>

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?

Best,

Jeremy