Re: [PATCH][2/2] RTAS MSI

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

> I'm only just starting to get benh's new irq code, but I think
> irq_find_host(dn) isn't doing what we want here. It's probably harmless,
> but AFAICT irq_find_host() is only meant to be called when you have the
> node of the irq controller, not for an arbitrary dn. The doco's a bit
> ambiguous:
> 
>  * irq_find_host - Locates a host for a given device node
>  * @node: device-tree node of the interrupt controller
> 
> But looking at the implementation, it doesn't do a search up the tree or
> anything, it just checks node against each host.

For pSeries, passing NULL is fine for host anyway as there is only one
domain that is relevant for MSIs (there might be a 8259 legacy domain
too but it's not relevant) and that domain is set to be the default
host.

> Also, since's benh's latest patch went in we'll have to split this into
> two calls, I think we want:
> 
> virq = irq_create_mapping(NULL ???, ret[0]);
> set_irq_type(virq, ret[1] ? IRQ_TYPE_EDGE_RISING : IRQ_TYPE_LEVEL_LOW);

MSIs are always edge (though there might be an issue with some P5IOC
errata lurking here...). The xics code doesn't care much at this point
though.

Ben.