On Mon, Mar 25, 2002 at 02:09:15PM -0800, David Brownell wrote:
> > usb-ohci.c: RET(rh) URB:[   0] dev: 0,ep: 0-O,type:CTRL,flags:   
>0,len:0/0,stat:0(0)
> > usb-ohci.c: USB Schedule overrun
> > usb-ohci.c: USB Schedule overrun
> > ... etc
> 
> Well that's curious.  OHCI isn't actually allowed to emit
> a schedule overrun interrupt until the periodic schedule
> has contents.  It's never going to have any at that point,
> since it will be completely empty (filled with zeroes, to
> indicate no contents).

That sounds bad.  :P

> You might try to disable OHCI_INTR_SO in the hc_start()
> routine.  That'll keep the controller from flooding your
> system with spurious schedule overrun interrupts (which
> likely caused the lockup).  (By the way, I'm assuming
> you're using a relatively recent kernel, not something
> from pre-history ... :)

This was with 2.4.18.  I took out OHCI_INTR_SO, and I've attached the 
resulting debug.  It isn't locking up any more, but now it seems to be
timing out when I attach a device (in this case, a cpia web cam).  I also 
tried another hub, and a CompactFlash reader.  Same results.

usb-ohci.c: USB new device connect on bus1/1, assigned device number 6
usb-ohci.c: SUB URB:[   0] dev: 0,ep: 0-O,type:CTRL,flags:   0,len:0/0,stat:0(0)
usb-ohci.c: cmd(8): 00 05 06 00 00 00 00 00
usb_control/bulk_msg: timeout
usb-ohci.c: UNLINK URB:[   0] dev: 0,ep: 0-O,type:CTRL,flags:   
0,len:0/0,stat:-115(ffffff8d)
usb-ohci.c: unlink URB timeout
usb.c: USB device not accepting new address=6 (error=-110)

Since this error is in the FAQ, I'm going to try disabling ACPI in the 
BIOS and the kernel.  Then I'll try noapic on bootargs.  I'll report back.

> As for why this silicon is deluded into thinking there's
> something in the periodic schedule that could overrun,
> I'm puzzled.  Though for the record, I've seen some
> other silicon do the same, and haven't figured out if
> it's the same issue.  Maybe someone's gone on a
> licensing binge with a flakey OHCI design ... :)

Ick.  Well, this is onboard a Gateway 6400 Server.  Not sure if that's 
useful information or not.

-- 
Kees Cook                                            @outflux.net

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