Re: [PATCH v3 3/7] irqchip: gic: Support hierarchy irq domain.

[Arnd Bergmann <arnd@arndb.de>]

On Monday 13 October 2014 09:56:20 Marc Zyngier wrote:
>         if (irq_domain_is_hierarchy(domain)) {
> +               if (domain->ops->xlate) {
> +                       /*
> +                        * If we've already configured this interrupt,
> +                        * don't do it again, or hell will break loose.
> +                        */
> +                       if (domain->ops->xlate(domain, irq_data->np,
> +                                              irq_data->args,
> +                                              irq_data->args_count,
> +                                              &hwirq, &type))
> +                               return 0;
> +
> +                       virq = irq_find_mapping(domain, hwirq);
> +                       if (virq)
> +                               return virq;
> +               }
>                 virq = irq_domain_alloc_irqs(domain, 1, NUMA_NO_NODE, irq_data);
>                 return virq <= 0 ? 0 : virq;
>         }
> 
> Thoughts?

Using irq_find_mapping() first is probably the right approach, that
is what irq_create_mapping() does too, and I suppose we want those
to be symmetric.

mt_sysirq_domain_alloc() in patch 4 has the irq_find_domain check
in it, which I guess we can remove when it has moved to the common
code.

I don't see irq_domain_alloc_irqs() in linux-next or older kernels, where
does that get introduced?

	Arnd