linux-kernel - Re: [PATCH v1 5/9] ACPI: processor: idle: Add the verification of processor FFH LPI state

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Message-ID: <CAJZ5v0iLt7rnXBaTBv=-ztKro39h1hECQS_Ov9Cn1eBcfhXDaQ@mail.gmail.com>
Date: Tue, 21 Oct 2025 21:42:30 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Huisong Li <lihuisong@...wei.com>
Cc: rafael@...nel.org, lenb@...nel.org, linux-acpi@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Sudeep.Holla@....com, linuxarm@...wei.com, 
	jonathan.cameron@...wei.com, zhanjie9@...ilicon.com, zhenglifeng1@...wei.com, 
	yubowen8@...wei.com
Subject: Re: [PATCH v1 5/9] ACPI: processor: idle: Add the verification of
 processor FFH LPI state

On Mon, Sep 29, 2025 at 11:38 AM Huisong Li <lihuisong@...wei.com> wrote:
>
> Both ARM64 and RISCV architecture would validate Entry Method of LPI
> state and SBI HSM or PSCI cpu suspend. Driver should return failure
> if FFH of LPI state are not ok.

First of all, I cannot parse this changelog, so I don't know the
motivation for the change.

Second, if _LPI is ever used on x86, the
acpi_processor_ffh_lpi_probe() in acpi_processor_get_power_info() will
get in the way.

Why does the evaluation in acpi_processor_setup_cpuidle_dev() not work?

> Fixes: a36a7fecfe60 ("ACPI / processor_idle: Add support for Low Power Idle(LPI) states")
> Signed-off-by: Huisong Li <lihuisong@...wei.com>
> ---
>  drivers/acpi/processor_idle.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> index 5684925338b3..b0d6b51ee363 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -1264,7 +1264,7 @@ static int acpi_processor_setup_cpuidle_dev(struct acpi_processor *pr,
>
>         dev->cpu = pr->id;
>         if (pr->flags.has_lpi)
> -               return acpi_processor_ffh_lpi_probe(pr->id);
> +               return 0;
>
>         return acpi_processor_setup_cpuidle_cx(pr, dev);
>  }
> @@ -1275,7 +1275,13 @@ static int acpi_processor_get_power_info(struct acpi_processor *pr)
>
>         ret = acpi_processor_get_lpi_info(pr);
>         if (ret)
> -               ret = acpi_processor_get_cstate_info(pr);
> +               return acpi_processor_get_cstate_info(pr);
> +
> +       if (pr->flags.has_lpi) {
> +               ret = acpi_processor_ffh_lpi_probe(pr->id);
> +               if (ret)
> +                       pr_err("Processor FFH LPI state is invalid.\n");
> +       }
>
>         return ret;
>  }
> --
> 2.33.0
>