[LAU] xruns with m-audio fast track pro on fedora 8 ccrma

hitmuri at no-log.org hitmuri at no-log.org
Tue Jan 22 05:33:51 EST 2008

Hi everyone,

i have posted this on the planet ccrma list before, but i don't think it's
a distribution problem. I get xruns when using a m-audio fast track pro
usb soundcard  at 44100Hz, frames/period=64 (same with 128, i need low
latency) ,periods/buffer=2 with my new laptop when i have for example
freewheeling, tapeutape and jack-rack running (xruns seem to appear when
the dsp load rises, i've got none when using tapeutape alone for example).
Some of them were related to the latest ccrma kernel, and they disappeared
with a previous one. For the other ones, i have 4 ideas :

1) latency timer :
doing lspci, all the latencies show 0 , even when i set them to antoher
value with setpci. But with dmesg, i can see that at startup they are set
to 64.
Fernando Lopez-Lezcano told me that on some hardware latency timer
couldn't be changed and that 64 could be enough actually.
(forgot to say that the usb irq isn't shared)

So it looks like i can't do anything for that.

2) rtc :
At startup i have a message from udev : Node Symlink... node /dev/rtc
already exists , link to /dev/rtc0 will not overwrite it.

3) soundcard power
The fast track pro can be powered by usb or by an external power supply.
Mine is usb powered for now. Is this a problem ?

4) rtirq
I noticed that in the rtirq script , i have these lines:
RTIRQ_NAME_LIST="rtc snd usb i8042"
Do they need to be changed when using a usb soundcard ?

If anyone has an idea on that...

Sorry it was quite long !!



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