On Tue, Nov 02, 2021 at 09:11:21AM +0900, Youngmin Nam wrote:
> Exynos MCT version 2 is composed of 1 FRC and 12 comparators.
> There are no global timer and local timer anymore.
> The 1 of 64bit FRC serves as "up-counter"(not "comparators").
> The 12 comaprators(not "counter") can be used as per-cpu event timer
> so that it can support upto 12 cores.
> And a RTC source can be used as backup clock source.
[...]
> +static int exynos_mct_starting_cpu(unsigned int cpu)
> +{
> + struct mct_clock_event_device *mevt = per_cpu_ptr(&percpu_mct_tick, cpu);
> + struct clock_event_device *evt = &mevt->evt;
> +
> + snprintf(mevt->name, sizeof(mevt->name), "mct_comp%d", cpu);
> +
> + evt->name = mevt->name;
> + evt->cpumask = cpumask_of(cpu);
> + evt->set_next_event = exynos_comp_set_next_event;
> + evt->set_state_periodic = mct_set_state_periodic;
> + evt->set_state_shutdown = mct_set_state_shutdown;
> + evt->set_state_oneshot = mct_set_state_shutdown;
> + evt->set_state_oneshot_stopped = mct_set_state_shutdown;
> + evt->tick_resume = mct_set_state_shutdown;
> + evt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
> + evt->rating = 500; /* use value higher than ARM arch timer */
Previously Will asked you to try CLOCK_EVT_FEAT_PERCPU here, and to set
the C3STOP flag on the arch timer via the DT when necessary, rather than
trying to override the arch timer like this:
https://lore.kernel.org/r/20211027073458.GA22231@willie-the-truck
There are a bunch of things that depend on the architected timer working
as a clocksource (e.g. vdso, kvm), and it *should* work as a lock
clockevent_device if configured correctly, and it's much more consistent
with *everyone else* to use the arhcitected timer by default.
Please try as Will suggested above, so that this works from day one.
Thanks,
Mark.
