On Wed, 28 Aug 2013, Udo van den Heuvel wrote:
> On 2013-08-27 19:43, Alan Stern wrote:
> >>> rmmod ohci-pci
> >>> modprobe dummy-irq irq=18
> >>>
> >>> and see if the IRQ line gets disabled after that.
> >>
> >> Can I actually use that irq/ports that way? (as with no usage the
> >> problem does not occur)
> >
> > No, if you unload the ohci-hcd driver then the webcam won't be used.
> > Are you certain that merely stopping the daemon program will prevent
> > the problem?
>
> Quite certain but retesting can confirm that.
Maybe without activity, the OHCI controller goes into suspend. You can
prevent it by doing:
echo on >/sys/bus/pci/devices/0000:00:13.1/usb?/power/control
If you do this and stop using the webcam, but leave ohci-hcd bound to
the controller, does the problem occur?
> >> No ohci_pci, is that a problem?
> >
> > Sorry, for 3.10 it should be ohci_hcd. In 3.11 it changed to ohci_pci.
>
> 3.10.9 is the latest here.
>
> > Have you tried getting a USB-2 hub and plugging the webcam into it?
> > That will make a good test: You'll be able to use the webcam without
> > it affecting the ohci-hcd driver.
>
> Not yet but I'll have hubs to test with soon.
>
> > As a second test, you can try plugging everything _except_ the webcam
> > into the hub.
>
> To see if the webcam itself is a factor. I see.
By the way, since you switched to the new computer, are there any
devices attached to this USB bus other than the webcam?
Also, at one point you had a second webcam attached to a different OHCI
controller, as well as a Bluetooth device and a USB-serial device.
Are they still present?
> This afternoon I found a 3.8.10 kernel with the disabled irq 18 and some
> ^@^@^@ characters on teh console.
> After I did:
>
> service motion stop
> rmmod pwc
> echo 0000:00:13.0 >/sys/bus/pci/drivers/ohci_hcd/unbind
> echo 0000:00:13.0 >/sys/bus/pci/drivers/ohci_hcd/bind
> modprobe pwc
> service motion start
>
> the ^@^@^@ appeared to stop.
> I'll try to watch /proc/interrupts to see if the ^@^@ correlate with
> i8042 interrupts.
Maybe they are related somehow, but I have no idea how.
Alan Stern
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