Hi Marc,
Marc Zyngier <marc.zyngier@xxxxxxx> wrote on Tue, 21 Aug 2018 11:37:47
+0100:
> On 21/08/18 11:28, Miquel Raynal wrote:
> > Hi Marc,
> >
> > Marc Zyngier <marc.zyngier@xxxxxxx> wrote on Tue, 21 Aug 2018 10:19:04
> > +0100:
> >
> >> On 21/08/18 10:08, Miquel Raynal wrote:
> >>> Hi Marc,
> >>>
> >>> I'm fine with the rest of the comments, please find just one last
> >>> question below.
> >>>
> >>> [...]
> >>>
> >>>>> @@ -133,12 +164,36 @@ mvebu_icu_irq_domain_translate(struct irq_domain *d, struct irq_fwspec *fwspec,
> >>>>> return -EINVAL;
> >>>>> }
> >>>>>
> >>>>> - /* Mask the type to prevent wrong DT configuration */
> >>>>> - *type = fwspec->param[2] & IRQ_TYPE_SENSE_MASK;
> >>>>> + /*
> >>>>> + * The ICU receives level-interrupts. MSI SEI are
> >>>>> + * edge-interrupts while MSI NSR are level-interrupts. Update the type
> >>>>> + * accordingly for the parent irqchip.
> >>>>> + */
> >>>>> + if (msi_data->subset_data->icu_group == ICU_GRP_SEI)
> >>>>> + *type = IRQ_TYPE_EDGE_RISING;
> >>>>
> >>>> That's interesting. How is the resampling done here?
> >>>
> >>> I'm not sure to understand the question. What does 'resampling' means
> >>> in such context? MSI SEIs are of type "edge" and use the traditional
> >>> MSI signalling infrastructure. I'm asking to be sure not to ignore
> >>> something wrong in my code.
> >>
> >> You seems to be turning a level interrupt into an edge.
> >
> > If is an SEI interrupt, it cannot be a level interrupt and the type
> > will be IRQ_TYPE_EDGE_RISING.
> >
> >> You can do that,
> >> but only if you resample the level on EOI (and regenerate the
> >> corresponding edge if the level is still high).
> >
> > What is before is a '& IRQ_TYPE_SENSE_MASK' operation. In theory,
> > *type could be anything of IRQ_TYPE_{EDGE,LEVEL}_* at this moment. But,
> > as stated above, it cannot be anything else than IRQ_TYPE_EDGE_RISING.
> > I thought more clear to enforce it but if this unclear and useless,
> > let's drop it?
>
> I think overriding the trigger that way is very confusing. Either it
> comes from DT, or it comes from the MSI framwork. In both cases, it has
> to be correct, and overriding it is just papering over other bugs.
>
> I'd rather you put a WARN_ON if you encounter an illegal interrupt trigger.
Fine by me.
Thanks for all the guidance, I'll send a new iteration ASAP (with the
bindings updated).
Thanks,
Miquèl
