[linux-audio-user] USX2Y rawusb mode

[Karsten Wiese]

Am Donnerstag 03 März 2005 16:32 schrieb Spencer Russell:
> On Thu, Mar 03, 2005 at 12:41:17PM +0100, Karsten Wiese wrote:
> >  
> > can you check if this error doesn't happen, when modprobing like 
> > 	$ modprobe snd_usb_usx2y nrpacks=4
> > ?
> > nrpacks=1 and "rawusb mode" are irrelevant if you run jack with moderate latencies
> > as above "-p1024 -n2" and 2 inputs.
> > 
> 
> With nrpacks=4, it seems to last slightly longer before giving
> the "Sequence Error!" and "Most propably some urb of usb-frame
> 935 is still missing"
> 

try with apm and acpi disabled.
append "apm=off acpi=off" to the kernels boot parameter line.
on laptops lots of things happen "beghind the scenes" .
"apm=off acpi=off" made a big differenc here when I used 2.4 kernels.

> > What kernel are you using? If its not 2.6.11 you might give that a try.
> 
> Every time I've tried using a 2.6 kernel on this machine, I get
> these random lockups that I can't figure out, so I'm using 2.4.26
> with lowlatency, preempt, and givecap patches. I'll try 2.6.11,
> and see how that goes.

also on 2.6.11 you'd disable apm & acpi like above to try to get rid 
of those random lockups or "Sequence Error!"s.

> 
> Rui said a while ago that he was getting a similar message, until
> he tuned the IRQ priorities, but I've been googling around and I
> can't figure out how to do it. I tried
> chrt -f -p 90 'pidof "IRQ 0"'
> as directed on some website, but it just returns
> 
> execvp: No such file or directory
> failed to execute pidof "IRQ 0"

this is for the realtime kernel patches by Ingo Molnar.
I may be wrong, but I'd suggest you get it running on 2.6.11 before you
proceed with the realtime kernels.
Plain 2.6.11 gives me better low latency (and better behavior with acpi enabled too) than
patched 2.4 kernels. lots of Ingo's enhancements are in 2.6.11 already.

Still the very basic mode with 
 	$ modprobe snd_usb_usx2y nrpacks=4
must work flawlessly with  2 in / 2 out jack like
	$ jackd -R -dalsa -dhw:0
on a plain kernel as first step.


> srussell at slingshot:~$ lsusb
> Bus 001 Device 001: ID 0000:0000  
> Bus 001 Device 002: ID 07a6:0986 ADMtek, Inc. AN986 Pegasus Ethernet
> Bus 001 Device 005: ID 1604:8001 Tascam US-428 Audio/Midi Controller

Your ethernet is also on usb!
Usb audio is enough to fully occupy an USB 1.1 bus.
Try with us428 as the only usb client (without that usb ethernet).

cheers
Karsten