[LAU] UA25 noise problem w. nVidia chipset

[Mark Knecht]

On Wed, Apr 6, 2011 at 3:34 PM, Dave Phillips <dlphillips at woh.rr.com> wrote:
> Greetings,
>
> I've been working with Ardour3 on my laptop, a machine with an AMD Turion X2
> CPU and an nVidia 8200M integrated video chipset. Recently I started
> monitoring my test recordings through the headphone output of my UA25 and I
> notice that when I move the mouse it creates scratchy sounds, though
> QJackCtl reports no xruns and my recordings are unaffected. I verified the
> problem with Ardour2 and Mixbus. It doesn't occur when I use the integrate
> audio chipset (snd-hda-intel, wahoo).
>
> Running 'cat /proc/interrupts' reports that usb1/usb3 share interrupt 17 and
> usb2/usb4 share interrupt 16. I've tried switching ports around but that
> didn't get rid of the noise. Any further suggestions ?
>
> Best,
>
> dp

What does

lsusb

and

lsusb -t

tell you? Are these two USB devices on different buses using different
controllers & different interrupts?

With no audio running if you move the mouse and watch /proc/interrupts
you should be able to see which interrupt is being used. HEre are a
couple of measurements. The first is a baseline. The second is the
system sitting quiet for 1 minute. Note that Int16 didn't change. The
third is after me moving the mouse for 1 minute. Clearly Int16 jumped
a lot, as expected.

I don't have a USB audio device but you can run the same tests using
USB audio and not using the mouse. (much)

This is a 12-core SMP machine which is why there are so many 0's in each row.

Hope this helps,
Mark

cat /proc/interrupts | grep usb

c2stable ~ # date && cat /proc/interrupts | grep usb
Wed Apr  6 15:48:00 PDT 2011
 16:     506693          0          0          0          0          0
         0          0          0          0          0          0
IO-APIC-fasteoi   ahci, uhci_hcd:usb3
 18:      35414          0          0          0          0          0
         0          0          0          0          0          0
IO-APIC-fasteoi   ehci_hcd:usb1, uhci_hcd:usb8
 19:          0          0          0          0          0          0
         0          0          0          0          0          0
IO-APIC-fasteoi   uhci_hcd:usb5, uhci_hcd:usb7
 21:          0          0          0          0          0          0
         0          0          0          0          0          0
IO-APIC-fasteoi   uhci_hcd:usb4
 23:          2          0          0          0          0          0
         0          0          0          0          0          0
IO-APIC-fasteoi   ehci_hcd:usb2, uhci_hcd:usb6
c2stable ~ # date && cat /proc/interrupts | grep usb
Wed Apr  6 15:49:00 PDT 2011
 16:     506693          0          0          0          0          0
         0          0          0          0          0          0
IO-APIC-fasteoi   ahci, uhci_hcd:usb3
 18:      35471          0          0          0          0          0
         0          0          0          0          0          0
IO-APIC-fasteoi   ehci_hcd:usb1, uhci_hcd:usb8
 19:          0          0          0          0          0          0
         0          0          0          0          0          0
IO-APIC-fasteoi   uhci_hcd:usb5, uhci_hcd:usb7
 21:          0          0          0          0          0          0
         0          0          0          0          0          0
IO-APIC-fasteoi   uhci_hcd:usb4
 23:          2          0          0          0          0          0
         0          0          0          0          0          0
IO-APIC-fasteoi   ehci_hcd:usb2, uhci_hcd:usb6
c2stable ~ # date && cat /proc/interrupts | grep usb
Wed Apr  6 15:50:00 PDT 2011
 16:     513590          0          0          0          0          0
         0          0          0          0          0          0
IO-APIC-fasteoi   ahci, uhci_hcd:usb3
 18:      35534          0          0          0          0          0
         0          0          0          0          0          0
IO-APIC-fasteoi   ehci_hcd:usb1, uhci_hcd:usb8
 19:          0          0          0          0          0          0
         0          0          0          0          0          0
IO-APIC-fasteoi   uhci_hcd:usb5, uhci_hcd:usb7
 21:          0          0          0          0          0          0
         0          0          0          0          0          0
IO-APIC-fasteoi   uhci_hcd:usb4
 23:          2          0          0          0          0          0
         0          0          0          0          0          0
IO-APIC-fasteoi   ehci_hcd:usb2, uhci_hcd:usb6
c2stable ~ #

- Mark