[PlanetCCRMA] sound card IRQ and crackling sound on F7

[Fernando Lopez-Lezcano]

On Tue, 2007-06-12 at 16:56 -0400, Hector Centeno wrote:
> Hi,
> 
> I'm having problems with my new motherboard (Asus P5B-VM with an Intel
> Core 2 Duo) and a M-Audio Audiphile PCI audio interface. My problem is
> mainly with Csound and getting crackling sound on one channel. If I
> set jack buffers to anything higher than 512x2 the crackling gets
> worse. I tried switching the card to the other PCI slot (it has only
> two) and the problem got even worse as I would get crackling audio
> always. I noticed that both PCI slots are sharing IRQ with other 3
> devices (usb, video card, libata). In the motherboards manual it says:
> 
> 1.8.2 Configuring an expansion card
> After installing the expansion card, configure it by adjusting the
> software settings.
> 1. Turn on the system and change the necessary BIOS settings, if any. See
> Chapter 4 for information on BIOS setup.
> 2. Assign an IRQ to the card. Refer to the tables on the next page.
> 3. Install the software drivers for the expansion card.
> 
> There is no more details about how to perform step 2, Chapter 4 only
> talks about reserving IRQ for ISA interfaces and in the bios there is
> no way to manually assign IRQs and it looks like it's something you
> are supposed to do va software, so I was wondering if anyone knows how
> to do IRQ assignment in Linux using the CCRMA kernel. With my older
> motherboard and FC6 it was possible to get the Audiophile to have it's
> own IRQ and I never had any problems with the audio (until the hard
> drive controllers in the mobo started to fail and had to replace it).

I would check the pci latency settings just in case that's the problem. 

Do a "/sbin/lspci -v" and see what numbers you have for the latency
parameter for the cards installed (included the video card). 

-- Fernando