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SubjectRe: mpic IRQ_TYPE_BOTH handling
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On 08/31/2017 01:52 AM, Michael Ellerman wrote:
> Hi Gregory,
>
> Gregory Fong <gregory.0xf0@gmail.com> writes:
>> Hi all,
>>
>> In arch/powerpc/sysdev/mpic.c , it looks like IRQ_TYPE_EDGE_BOTH is
>> handled the same way as IRQ_TYPE_EDGE_FALLING:
>>
>> static unsigned int mpic_type_to_vecpri(struct mpic *mpic, unsigned int type)
>> {
>> /* Now convert sense value */
>> switch(type & IRQ_TYPE_SENSE_MASK) {
>> case IRQ_TYPE_EDGE_RISING:
>> return MPIC_INFO(VECPRI_SENSE_EDGE) |
>> MPIC_INFO(VECPRI_POLARITY_POSITIVE);
>> case IRQ_TYPE_EDGE_FALLING:
>> case IRQ_TYPE_EDGE_BOTH:
>> return MPIC_INFO(VECPRI_SENSE_EDGE) |
>> MPIC_INFO(VECPRI_POLARITY_NEGATIVE);
>> case IRQ_TYPE_LEVEL_HIGH:
>> return MPIC_INFO(VECPRI_SENSE_LEVEL) |
>> MPIC_INFO(VECPRI_POLARITY_POSITIVE);
>> case IRQ_TYPE_LEVEL_LOW:
>> default:
>> return MPIC_INFO(VECPRI_SENSE_LEVEL) |
>> MPIC_INFO(VECPRI_POLARITY_NEGATIVE);
>> }
>> }
>>
>> If IRQ_TYPE_EDGE_BOTH is unsupported, shouldn't we be returning an
>> error, instead of silently setting to use IRQ_TYPE_EDGE_FALLING?
>> Something like the following (sorry if the diff wraps weirdly, on
>> webmail at the moment):
>
> I don't know this code so I asked Ben and he said something like
> "PowerMacs never use BOTH, so it hasn't mattered, but Freescale machines
> might".

IIRC, the mpic in freescale MPICs the interrupts are either low or high,
so not both. There's a bit which controls the interrupt polarity which
selects if the interrupt triggers on high-to-low or low-to-high.
So i guess it doesn't matter on freescale machines too.

---
Best Regards, Laurentiu
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