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SubjectRe: [PATCH v2 -rt] ide: workaround buggy hardware issues with preemptable hardirqs
Hello.

Anton Vorontsov wrote:
>>> But some hardware (namely ULi M5228 in the ULi M1575 "Super South Brige")
>>> behaves in a strange way: it asserts interrupts as edge sensitive. And
>>> because preemptable IRQ handler disables PIC's interrupt, PIC will likely
>>> miss it.
>>>
>>>
>> Unmasking an IRQ should re-enable an edge detector in a PIC (or that
>> detector should even be independent from mask).
>>
> Should? Hm.. well, I can easily check it. Will just program the MPIC IRQ
> to edge sensitive, and see if it fixes the problem (not sure if I already
> tried this, I think I did try).
>

That will not help if edge detector is not active for masked out IRQs
(that's how i8259 behaves, IIRC) *and* you're getting the short IRQ
"pulses" but should help if IRQ is generated normally -- though in this
case the level trigger mode (with the same polarity) should work as well...

MBR, Sergei




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