The scheduling overrun interrupt can only occur when the OHCI controller
determines that it cannot complete its periodic tasks within the  1 ms time
frame.  While this can technically happen, you would have to have heavy
isochronous (e.g. audio) traffic for it to occur.
If there are no USB devices connected it cannot happen.  With no audio
running I cannot see how it could happen.
So if it happens, there's a bug somewhere.  In the chip or in the driver.
Having written the driver, I'll blame the chip. :-)

    -- Lennart


Chris Gilbert wrote:

> On Thursday 17 May 2001 10:52 am, Thilo Manske wrote:
> > On Wed, May 16 2001 at 23:06:33 +0100, Chris Gilbert wrote:
> > > on my arm32 CATS box I've been getting:
> > > ohci0: scheduling overrun
> > >
> > > And I was wondering if anyone else was seeing it.
> >
> > Yes, I used to get this on i386.
> >
> > But they look more like this:
> > "ohci0: n scheduling overruns"
> >
> > with n=1..6
> >
> > It's the onboard USB interface of on Asus P5A, ALi Chipset.
> > I don't have USB in my kernel anymore, so I can't quote a better dmesg
> > snippet than this:
> >
> > vendor 0x10b9 product 0x5237 (USB serial bus, interface 0x10, revision
> > 0x03) at pci0 dev 2 function 0 not configured
>
> The CATS runs:
> ohci0 at pci0 dev 20 function 0: Acer Labs M5237 USB Host Controller
> (rev.0x03)
> So perhaps it's a bug/quirk of ALi USB and/or our driver.
>
> Cheers,
> Chris