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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Tue, 12 Dec 2023 14:47:36 +0100
Message-ID: <CAJZ5v0ghO8A2co6tK6-kM-1NdjVggM-_26hj+oiv8hTGQGg1mw@mail.gmail.com>
Subject: Re: [PATCH V12 2/7] acpi: cppc: Add get the highest performance cppc control
To:     Meng Li <li.meng@amd.com>
Cc:     "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
        Huang Rui <ray.huang@amd.com>, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org, x86@kernel.org,
        linux-acpi@vger.kernel.org, Shuah Khan <skhan@linuxfoundation.org>,
        linux-kselftest@vger.kernel.org,
        Nathan Fontenot <nathan.fontenot@amd.com>,
        Deepak Sharma <deepak.sharma@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        Mario Limonciello <mario.limonciello@amd.com>,
        Shimmer Huang <shimmer.huang@amd.com>,
        Perry Yuan <Perry.Yuan@amd.com>,
        Xiaojian Du <Xiaojian.Du@amd.com>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Borislav Petkov <bp@alien8.de>,
        Oleksandr Natalenko <oleksandr@natalenko.name>,
        Wyes Karny <wyes.karny@amd.com>
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Please spell ACPI and CPPC in capitals in the subject.

On Tue, Dec 5, 2023 at 7:38 AM Meng Li <li.meng@amd.com> wrote:
>
> Add support for getting the highest performance to the
> generic CPPC driver. This enables downstream drivers
> such as amd-pstate to discover and use these values.
>
> Please refer to the ACPI_Spec for details on continuous
> performance control of CPPC.

So which section of the spec is the reader supposed to refer to?

> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
> Reviewed-by: Wyes Karny <wyes.karny@amd.com>
> Reviewed-by: Perry Yuan <perry.yuan@amd.com>
> Acked-by: Huang Rui <ray.huang@amd.com>
> Signed-off-by: Meng Li <li.meng@amd.com>
> Link: https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html?highlight=cppc#highest-performance
> ---
>  drivers/acpi/cppc_acpi.c | 13 +++++++++++++
>  include/acpi/cppc_acpi.h |  5 +++++
>  2 files changed, 18 insertions(+)
>
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index 7ff269a78c20..ad388a0e8484 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -1154,6 +1154,19 @@ int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf)
>         return cppc_get_perf(cpunum, NOMINAL_PERF, nominal_perf);
>  }
>
> +/**
> + * cppc_get_highest_perf - Get the highest performance register value.
> + * @cpunum: CPU from which to get highest performance.
> + * @highest_perf: Return address.
> + *
> + * Return: 0 for success, -EIO otherwise.
> + */
> +int cppc_get_highest_perf(int cpunum, u64 *highest_perf)
> +{
> +       return cppc_get_perf(cpunum, HIGHEST_PERF, highest_perf);
> +}
> +EXPORT_SYMBOL_GPL(cppc_get_highest_perf);
> +
>  /**
>   * cppc_get_epp_perf - Get the epp register value.
>   * @cpunum: CPU from which to get epp preference value.
> diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h
> index 6126c977ece0..c0b69ffe7bdb 100644
> --- a/include/acpi/cppc_acpi.h
> +++ b/include/acpi/cppc_acpi.h
> @@ -139,6 +139,7 @@ struct cppc_cpudata {
>  #ifdef CONFIG_ACPI_CPPC_LIB
>  extern int cppc_get_desired_perf(int cpunum, u64 *desired_perf);
>  extern int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf);
> +extern int cppc_get_highest_perf(int cpunum, u64 *highest_perf);
>  extern int cppc_get_perf_ctrs(int cpu, struct cppc_perf_fb_ctrs *perf_fb_ctrs);
>  extern int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls);
>  extern int cppc_set_enable(int cpu, bool enable);
> @@ -165,6 +166,10 @@ static inline int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf)
>  {
>         return -ENOTSUPP;
>  }
> +static inline int cppc_get_highest_perf(int cpunum, u64 *highest_perf)
> +{
> +       return -ENOTSUPP;
> +}
>  static inline int cppc_get_perf_ctrs(int cpu, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
>  {
>         return -ENOTSUPP;
> --