Re: [Xen-devel] [PATCH v5 2/6] xen/arm: IRQ: Store IRQ type in arch_irq_desc

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2014-05-02 at 16:52 +0100, Julien Grall wrote:
> For now, ARM uses different IRQ functions to setup an interrupt handler. This
> is a bit annoying for common driver because we have to add idefery when
> an IRQ is setup (see ns16550_init_postirq for an example).
> 
> To avoid to completely fork the IRQ management code, we can introduce a field
> to store the IRQ type (e.g level/edge ...).
> 
> This patch also adds platform_get_irq which will retrieve the IRQ from the
> device tree and setup correctly the IRQ type.
> 
> In order to use this solution, we have to move init_IRQ earlier for the boot
> CPU. It's fine because the code only depends on percpu.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>

Looks good. But based on the comments raised previously I am wondering
if 
        static int ppi_types[NR_PPIS]
which is set on configuration of such an interrupt and propagated to the
cpu local copy when a CPU comes up?

Apart from avoiding the slightly odd per_cpu(0) (even if hidden behind a
macro) it also means that there is less need to be concerned about which
processor ends up initialising an interrupt, which would simplify some
stuff around irq_set_type and platform_get_irq (essentially you could
then sanity check the change against ppi_types and then propagate to all
online cpus without further checks).

Thoughts?


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