mpic IRQ_TYPE_BOTH handling

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):

----8<----
        /* We don't support "none" type */
---->8----

Thanks,
Gregory

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".

So if you want to send a proper signed-off patch, and confirm that all
the callers can handle the error properly, then we can merge it.

cheers

> ----8<----
> diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
> index b9aac95..5867ea2 100644
> --- a/arch/powerpc/sysdev/mpic.c
> +++ b/arch/powerpc/sysdev/mpic.c
> @@ -876,6 +876,9 @@ int mpic_set_irq_type(struct irq_data *d, unsigned
> int flow_type)
>         if (src >= mpic->num_sources)
>                 return -EINVAL;
>
> +       if (flow_type & IRQ_TYPE_SENSE_MASK == IRQ_TYPE_EDGE_BOTH)
> +               return -EINVAL;
> +
>         vold = mpic_irq_read(src, MPIC_INFO(IRQ_VECTOR_PRI));
>
>         /* We don't support "none" type */
> ---->8----
>
> Thanks,
> Gregory

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