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.