Subject: Re: [linux-audio-user] Just bought a Delta 1010LT, now what..?
From: Lee Revell (rlrevell_AT_joe-job.com)
Date: Sat Sep 25 2004 - 22:47:25 EEST
On Sat, 2004-09-25 at 12:52, Jan Depner wrote:
> You definitely want to turn off acpi. I didn't turn USB off since I use
> it fro uploading pictures from my camera. Try moving the 1010LT card
> around to see if you can get it on IRQ 9 or 10 by itself. I have almost
> the same setup and I have:
>
> CPU0
> 0: 15340768 XT-PIC timer
> 1: 6854 XT-PIC keyboard
> 2: 0 XT-PIC cascade
> 5: 0 XT-PIC usb-uhci, usb-uhci
> 8: 1 XT-PIC rtc
> 10: 33774 XT-PIC ICE1712
> 11: 1858859 XT-PIC eth0, nvidia
> 12: 351739 XT-PIC PS/2 Mouse
> 14: 627800 XT-PIC ide0
> 15: 1548341 XT-PIC ide1
>
> It took me a few tries to get it to this point. Note that I don't have
> anything on IRQ 9. I was unable to get it there but since I got IRQ 10
> for my card it's OK.
>
Actually, you should probably leave it alone. The important thing is
not which IRQ it's on, it's more important that the IRQ not be shared.
Once you start moving PCI cards around you might have a hard time
getting the system to put the sound card on a non-shared IRQ.
The interrupt priorities mentioned by the previous poster are not a big
deal here. I believe these only determine which interrupt the CPU sees
first if they happen to fire at the *exact* same time. But, Linux
allows interrupts to nest (aka to interrupt other interrupts). So, even
if you get a USB and a soundcard interrupt at the exact same time and
the processor sees the USB one first, the soundcard interrupt will
literally interrupt the USB interrupt handler. So interrupts are
serviced immediately, even if the system is alreasy handling another
interrupt. Anyway, this is all a matter of nanoseconds or microseconds,
not enough to affect audio latency.
ACPI can definitely cause problems, but if it seems to be working,
there's no reason to disable it.
Lee
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