Re: [PATCH v2 4/5] clocksource: mips-gic-timer: Set next GIC event on the correct VP

[Thomas Gleixner]

On Mon, Aug 10 2026 at 16:25, Benoît Monin wrote:
> gic_next_event() programs the next event on the clock_event_device's target
> CPU. When that CPU is not the current one, the compare register is reached
> through the GIC VO (other/redirect) window, which is first pointed at the
> target VP with write_gic_vl_other().
>
> On a multi-cluster system each cluster has its own GIC. The VO window of
> the local GIC is what write_gic_vl_other() redirects, so when the target
> CPU belongs to another cluster, write_gic_vo_compare() lands in the
> wrong GIC, overwriting the COMPARE register of a VP in the local cluster.

The MIPS GIC clockevent device is strictly registered per CPU with the
cpumask of that CPU. See gic_clockevent_cpu_init().

The set_next_event() callback of a per CPU clockevent device is _always_
invoked on that CPU and cannot be invoked on a different CPU.

So I completely fail to understand what this cluster and non-current CPU
voodoo is about.

Thanks,

        tglx