linux-kernel - Re: [PATCH] ACPI: CPPC: Don't require flexible address space if X86_FEATURE

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Date:   Mon, 18 Jul 2022 20:42:02 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Mario Limonciello <mario.limonciello@....com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Pierre Gondois <pierre.gondois@....com>,
        Sudeep Holla <sudeep.holla@....com>,
        "Yuan, Perry" <perry.yuan@....com>,
        Arek Ruśniak <arek.rusi@...il.com>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ACPI: CPPC: Don't require flexible address space if
 X86_FEATURE_CPPC is supported

On Fri, Jul 15, 2022 at 7:33 PM Mario Limonciello
<mario.limonciello@....com> wrote:
>
> commit 0651ab90e4ad ("ACPI: CPPC: Check _OSC for flexible address space")
> changed _CPC probing to require flexible address space to be negotiated
> for CPPC to work.
>
> However it was observed that this caused a regression for Arek's ROG
> Zephyrus G15 GA503QM which previously CPPC worked, but now it stopped
> working.
>
> To avoid causing a regression waive this failure when the CPU is known
> to support CPPC.
>
> Cc: Pierre Gondois <pierre.gondois@....com>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=216248
> Fixes: 0651ab90e4ad ("ACPI: CPPC: Check _OSC for flexible address space")
> Reported-and-tested-by: Arek Ruśniak <arek.rusi@...il.com>
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
>  drivers/acpi/cppc_acpi.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index 6ff1901d7d43..3c6d4ef87be0 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -782,7 +782,8 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
>
>                                         if (!osc_cpc_flexible_adr_space_confirmed) {
>                                                 pr_debug("Flexible address space capability not supported\n");
> -                                               goto out_free;
> +                                               if (!cpc_supported_by_cpu())
> +                                                       goto out_free;
>                                         }
>
>                                         addr = ioremap(gas_t->address, gas_t->bit_width/8);
> @@ -809,7 +810,8 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
>                                 }
>                                 if (!osc_cpc_flexible_adr_space_confirmed) {
>                                         pr_debug("Flexible address space capability not supported\n");
> -                                       goto out_free;
> +                                       if (!cpc_supported_by_cpu())
> +                                               goto out_free;
>                                 }
>                         } else {
>                                 if (gas_t->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE || !cpc_ffh_supported()) {
> --

Applied as 5.19-rc material, thanks!