Re: [RFC PATCH 7/7] irqchip/apple-aic: add SMP support to the Apple AIC driver.

From: Marc Zyngier
Date: Thu Jan 21 2021 - 09:07:23 EST

On 2021-01-21 13:32, Mark Rutland wrote:
On Thu, Jan 21, 2021 at 01:22:37PM +0000, Marc Zyngier wrote:
On 2021-01-21 12:50, Mohamed Mediouni wrote:
> > On 21 Jan 2021, at 13:44, Arnd Bergmann <arnd@xxxxxxxxxx> wrote:
> >
> > On Wed, Jan 20, 2021 at 2:27 PM Mohamed Mediouni


> > > + aic.fast_ipi = of_property_read_bool(node, "fast-ipi");
> >
> > Where is this property documented, and what decides which one to use?
> It’s getting documented in the next patch set.
> This property is there to enable support for older iPhone processors
> later on, some of which do not have fast IPI support.
> On Apple M1, fast-ipi is always on.

Then please focus on a single implementation. Additional features can
always be merged later once something is up and running.

Also, there sysregs can be detected by matching the MIDR, so I don't
think we need a DT property for that.

Generally we do not detect IMP-DEF sysregs based on MIDR because they
won't necessarily be exposed to a VM, so I suspect that we do need DT
properties to describe that IMP-DEF sysregs are accessible, and should
not rely on the MIDR alone. Maybe that's implicit in another property,
but worth bearing in mind.

Hmm. That's a good point. I think this could be keyed off
the compatible property, which should accurately reflect
the version of the interrupt controller.


Jazz is not dead. It just smells funny...