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[Linux-am33-list] Re: [PATCH 1/2] MN10300: Move asm-arm/cnt32_to_63.h to include/linux/



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and writes __m_cnt_hi, it corrupts it with an out of date value.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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