Re: [PATCH v2 14/25] dt-bindings: interrupt-controller: Add DT bindings for apple-aic

Mark Kettenis
2021-02-16T11:02:17Z

> From: Arnd Bergmann <arnd@kernel.org>
> Date: Tue, 16 Feb 2021 10:41:11 +0100
>
> On Mon, Feb 15, 2021 at 1:17 PM Hector Martin <marcan@marcan.st> wrote:
> > +
> > + The 2nd cell contains the interrupt number.
> > + - HW IRQs: interrupt number
> > + - FIQs:
> > + - 0: physical HV timer
> > + - 1: virtual HV timer
> > + - 2: physical guest timer
> > + - 3: virtual guest timer
>
> I wonder if you could just model the FIQ as a single shared level interrupt
> (which is essentially what it is), and have every driver that uses it do a
> request_irq() on the same IRQ number.
>
> This would avoid having to come up with a fake binding for it, and simplify
> the implementation that then no longer has to peek into each interrupt
> source.

That would tie the binding more closely to the implementation as it
would remove the option of peeking at the interrupt source. And
wouldn't it mean that the arch_timer driver would need to know whether
the interrupt is shared or not?