[PATCH] qe_ic: Do a sync when masking interrupts.
segher at kernel.crashing.org
Tue Oct 24 04:46:01 EST 2006
>> If a sync after an MMIO write is enough, then (in almost all
>> cases) so is an eieio.
> In this case, the spurious interrupts still happen with eieio, but
> not with sync. It's probably synchronizing the MMIO write with
> some unrelated load from memory (such as reading the stack frame to
> return from the mask function, or reading action->flags to
> determine whether to check for IRQ_DISABLED).
Yes, it sure sounds like the only reason the sync insn helps
is that it causes a (small) delay. If you document this (and
also that it isn't required for correctness) in the code, I
don't think anyone will complain / be curious about it anymore.
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