Re: [PATCH] ACPI: arm64: cpuidle: Tolerate platforms with no deep PSCI idle states

[Breno Leitao <leitao@debian.org>]

On Mon, Apr 20, 2026 at 04:12:38PM +0100, Sudeep Holla wrote:
> On Mon, Apr 20, 2026 at 02:27:13AM -0700, Breno Leitao wrote:
> > -	count = pr->power.count - 1;
> > -	if (count <= 0)
> > -		return -ENODEV;
> > -
>
> Does it make sense to retain this check like
>   if (pr->power.count < 1)
>   	return -EINVAL;
>
> Though I see the assignment to pr->power.count in drivers/acpi/processor_idle.c
> is through unsigned int. So I am fine even without the above check.

I don't think the check is necessary. When count is 0 or 1, the loop
for (i = 1; i < pr->power.count; i++) body won't execute, and the
function will return 0.

This seems like the correct behavior — if there are no FFH PSCI states
to validate, there's nothing that should fail.

Additionally, returning -ENODEV would trigger the "Invalid FFH LPI data"
error message, which would be misleading since the LPI data isn't
invalid, it's just not present.

That said, please take this with a grain of salt since I'm not deeply
familiar with _LPI states and their expected behavior.

Thanks for the review,
--breno