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    SubjectRe: OHCI root_port_reset() deadly loop...
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    From: Greg KH <greg@kroah.com>
    Date: Mon, 8 Oct 2007 20:10:49 -0700

    > Yes it does, I'm seeing reports from some hardware companies of the very
    > same thing. If you serialize and load the ehci driver first, and then
    > the ohci driver, that should fix the problem.
    >
    > Does that also work for you? Or are these drivers built into the
    > kernel?

    As coicidence would have it I finally found a recipe for triggering
    the issue, and it ties into what you're talking about here.

    It happens only if I make sure OHCI gets loaded first and then EHCI
    right afterwards.

    It seems that indeed it is important for EHCI to get loaded first,
    and in-kernel this is ensured by the link ordering.

    However, when both OHCI and EHCI are built as modules (or, similarly
    I guess, OHCI is built-in and EHCI is modular) there appears to be
    nothing in userspace which makes sure EHCI gets loaded first.

    When this triggers, in OHCI's root_port_reset(), the port status
    register reads 0x111 in that inner-loop and the value never changes.
    It stays like this forever.
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