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    SubjectRe: Strange EHCI/OHCI IRQ and other PCI errors on boot with 2.6.32 (which 2.6.26 did not see) on Geode LX/CS5536.
    On Wed, Jan 20, 2010 at 08:52:03PM -0500, Alan Stern wrote:
    > You could try changing the set of drivers loaded in memory. For
    > example, after booting with irqpoll you can unload ehci-hcd plus some
    > other driver, and then load ehci-hcd again. If the IRQ storm occurs
    > then you'll know where to look.
    > > > Does 2.6.26 fail on the new machine?
    > >
    > > Yes.
    > >
    > > As far as I can tell some machines don't see the problem. I am still
    > > investigating that.
    > Same kernel, initramfs, and everything else?

    Same 2.6.26 kernel, there is no initramfs involved. Some user space
    code has been updated on this one.

    > What I meant was: Is your current 2.6.26 still built using the same
    > .config as the old 2.6.26 which used to work okay?

    I haven't actually rebuilt 2.6.26. It is the same kernel image.

    I wonder if some of the cpu modules have a flaw that's making the IRQ
    line go crazy. I wasn't normally using it before except when a cellular
    usb modem was installed.

    I will try booting the same release of software on my box as the one
    that works and see if it still sees a problem...

    So it turns out every box behaves the same, but only if I change the
    order things are loaded in. If I load the usb driver before programming
    the FPGA on the LPC bus, then I get the IRQ flood. If I program the
    FPGA first, then no problem. I don't understand why since the LPC bus
    has been told not to handle IRQ 5 at all, and the FPGA has the pin tri
    stated and it is pulled up as per LPC SERIRQ spec, yet somehow it is
    driving the system mad. So the whole problem seems to be that by
    adding udev I made usb load earlier than it used to, and then when
    I tried building USB into the kernel instead, it loads even earlier,
    and in both cases it complains. Previously I just loaded things manually
    in the order that made sense, but I really want to go to more modern
    ways of doing things. I guess I will have to tell udev to ignore the
    usb controller and load that one manually after the FPGA. At least
    things make some sense now.

    Len Sorensen

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