[LAU] irq sharing

david gnome at hawaii.rr.com
Thu Aug 26 19:45:05 UTC 2010

Mark Knecht wrote:
> On Thu, Aug 26, 2010 at 2:08 AM, david <gnome at hawaii.rr.com> wrote:
>> David Santamauro wrote:
>>> Hi,
>>> On Tue, 24 Aug 2010 12:46:06 -0700
>>> Niels Mayer <nielsmayer at gmail.com> wrote:
>>>> On Tue, Aug 24, 2010 at 8:13 AM, David Santamauro <
>>>> david.santamauro at gmail.com> wrote:
>>>>> thanks for the time. I only have one PCI slot, but 3 empty PCI-x
>>>>> slots.
>>>>> I basically unplugged all USB devices as well as shut off both
>>>>> network interfaces and on board audio interface in the bios and the
>>>>> noise persists ...
>>>>> Not sure what to try next, this was a shot-in-the-dark.
>>>> If you think it's a interrupt-sharing issue, consider using a
>>>> pcie-to-pci riser to plug in your card. Apparently, this way of doing
>>>> things may ensure less bus contention:
>>>> http://old.nabble.com/does-a-pci-e-x1-to-pci-adapter-work-with-Linux-soundcards-and-existing-drivers--td29444687.html
>>>> Also, be sure that interrupt contention is really the problem. If
>>>> it's a constant noise, there's a better chance that it's a different
>>>> problem. One issue is that your recording software may not be using
>>>> the same bit depth, alignment, or complement as what the card
>>>> expects. I can get this effect on output, for example, simply by
>>>> using 'mplayer'
>>> interesting angle ...
>>> envy24control (and the new mudita24) register this noise on input
>>> whether devices are plugged in or not. So the noise is clearly coming
>>> from either the delta breakout, card or driver. I've ruled out the
>>> breakout box and card simply by the fact that the noise doesn't exist
>>> on the same hardware with windows7 drivers.
>> Or the Windows drivers are doing something that removes the noise?
>> I have a friend who has a Delta 1010LT in his WindowsXP-based audio
>> workstation. He's never said anything about input noise.
> That would imply that everyone using a 1010LT in Linux would
> experience the same noise, correct?
> If I understand, you are saying that the card, with nothing plugged
> into it, shows noise coming out of the card? If so it sounds like a
> bad card.

Oh, I'm not the original poster. Although that could be something the 
original poster might try. IIRC, he mentioned that the noise isn't there 
under Windows7 or 32-bit Linux. Only 64-bit Linux.

> If he's local can you ask your Windows friend to plug your card into
> his system for testing and see if it's noisy or not? Good weekend
> project if he's game.

That's worth checking.

Another a idea for original poster: Boot your existing hardware from a 
live Linux audio distro such as Ubuntu Studio or Musix or ArtistX or 
some such, and see if the noise exists. Just in case it's some obscure 
setting somewhere?

gnome at hawaii.rr.com
authenticity, honesty, community

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