linux-kernel - Re: [PATCH v2 3/7] ACPI: processor: idle: Relocate and verify acpi_processor_ffh_lpi

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Message-ID: <CAJZ5v0gf=eTuY_CoUDSp94Naj3fxjapc_FWYY+nBjX6qvvM_cg@mail.gmail.com>
Date: Mon, 3 Nov 2025 18:56:19 +0100
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 v2 3/7] ACPI: processor: idle: Relocate and verify acpi_processor_ffh_lpi_probe

On Mon, Nov 3, 2025 at 9:42 AM Huisong Li <lihuisong@...wei.com> wrote:
>
> The platform used LPI need check if the LPI support and the entry
> method is valid by the acpi_processor_ffh_lpi_probe(). But the return
> of acpi_processor_ffh_lpi_probe() in acpi_processor_setup_cpuidle_dev()
> isn't verified by any caller.
>
> What's more, acpi_processor_get_power_info() is a more logical place for
> verifying the validity of FFH LPI than acpi_processor_setup_cpuidle_dev().
> So move acpi_processor_ffh_lpi_probe() from the latter to the former and
> verify its return.
>
> Fixes: a36a7fecfe60 ("ACPI / processor_idle: Add support for Low Power Idle(LPI) states")

If you want to add this Fixes: tag, please add some information on
what systems it breaks on and what the symptoms are to the changelog.

> 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 5213a545fa78..c73df5933691 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -1266,7 +1266,7 @@ 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);
>  }
> @@ -1277,7 +1277,13 @@ 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;
>  }
> --