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    SubjectRe: [PATCH 1/2] MN10300: Move asm-arm/cnt32_to_63.h to include/linux/
    Date
    Nicolas Pitre <nico@cam.org> wrote:

    > If so then you're using this interface in an inappropriate way.
    >
    > The _absolute_ minimum frequency with which this should be fully
    > executed is once per half period of the base counter. I hope that in
    > practice it happens far more often than that.

    I think you're misunderstanding my contention.

    If preemption is enabled, cnt32_to_63() can be called with greater than
    minimum frequency and yet reversions can still happen.

    The problem is that a process that's half way through executing cnt32_to_63()
    can be preempted for a period of time sufficient that when it is rescheduled
    and writes __m_cnt_hi, it corrupts it with an out of date value.

    David



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