Re: [PATCH 3/3] soc: samsung: exynos-pmu: fix error paths in cpuhotplug/idle states setup

[Peter Griffin]

Hi Alexey,

On Mon, 22 Jun 2026 at 19:57, Alexey Klimov <alexey.klimov@xxxxxxxxxx> wrote:
[..]
> >> >
> >> > I originally made the failure non-fatal because the system still boots
> >> > without the notifiers registered (and all other Arm64 Exynos SoCs
> >> > upstream don't register notifiers and AFAICT have broken cpu hotplug
> >> > and cpu idle).
> >> >
> >> > In hindsight, that seems like a mistake. I think your patch to fully
> >> > unwind everything in case of failure makes more sense.  See small
> >> > comment below about destroy_cpuhp_and_cpuidle()
> >>
> >> Wait, setup_cpuhp_and_cpuidle() should be non-fatal and shouldn't
> >> return any errors?
> >
> > I suggest you re-read my above comment above ^^
>
> Could you please clarify what specifically addresses my question about
> notifiers?

Sure, I was referring to this part of my previous reply:

> >> > In hindsight, that seems like a mistake. I think your patch to fully
> >> > unwind everything in case of failure makes more sense.

[..]
>
> If c2 idles are used during reboot/shutdown then they fail or what?

This followed similar logic to the Samsung downstream kernel drivers.
I have no extra information about it beyond the downstream kernel
source. It seemed reasonable though that CPU's will be hotplugged
during suspend and reboot so you may wish to ignore these.

The proper solution of course is a fully PSCI compliant firmware,
which doesn't require these side channel hints.

>
> I am not saying that patch is correct and some rework is needed but I don't
> get why we should completely ignore errors from hotplug states registration
> and should not check registration of notifiers. At least warning should be
> shown to user that pm functionality might be unreliable.

As mentioned above, and in my previous reply, I think your proposed
patch is a good idea.

regards,

Peter