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

[Marc Zyngier]

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.

Thanks,

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