linux-kernel - Re: [PATCH v9 01/13] ACPI: CPPC: Add AMD pstate energy performance preference cppc control

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Date:   Thu, 5 Jan 2023 11:01:15 +0530
From:   Wyes Karny <wyes.karny@....com>
To:     Perry Yuan <perry.yuan@....com>, rafael.j.wysocki@...el.com,
        Mario.Limonciello@....com, ray.huang@....com,
        viresh.kumar@...aro.org
Cc:     Deepak.Sharma@....com, Nathan.Fontenot@....com,
        Alexander.Deucher@....com, Shimmer.Huang@....com,
        Xiaojian.Du@....com, Li.Meng@....com, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 01/13] ACPI: CPPC: Add AMD pstate energy performance
 preference cppc control



On 12/25/2022 10:04 PM, Perry Yuan wrote:
> From: Perry Yuan <Perry.Yuan@....com>
> 
> Add support for setting and querying EPP preferences to the generic
> CPPC driver.  This enables downstream drivers such as amd-pstate to discover
> and use these values.
> 
> Downstream drivers that want to use the new symbols cppc_get_epp_caps
> and cppc_set_epp_perf for querying and setting EPP preferences will need
> to call cppc_set_epp_perf to enable the EPP function firstly.
> 
> Reviewed-by: Mario Limonciello <mario.limonciello@....com>
> Signed-off-by: Perry Yuan <Perry.Yuan@....com>

Reviewed-by: Wyes Karny <wyes.karny@....com>

> ---
>  drivers/acpi/cppc_acpi.c | 67 ++++++++++++++++++++++++++++++++++++++++
>  include/acpi/cppc_acpi.h | 12 +++++++
>  2 files changed, 79 insertions(+)
> 
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index 093675b1a1ff..0ce6c55a76ca 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -1153,6 +1153,19 @@ int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf)
>  	return cppc_get_perf(cpunum, NOMINAL_PERF, nominal_perf);
>  }
>  
> +/**
> + * cppc_get_epp_perf - Get the epp register value.
> + * @cpunum: CPU from which to get epp preference value.
> + * @epp_perf: Return address.
> + *
> + * Return: 0 for success, -EIO otherwise.
> + */
> +int cppc_get_epp_perf(int cpunum, u64 *epp_perf)
> +{
> +	return cppc_get_perf(cpunum, ENERGY_PERF, epp_perf);
> +}
> +EXPORT_SYMBOL_GPL(cppc_get_epp_perf);
> +
>  /**
>   * cppc_get_perf_caps - Get a CPU's performance capabilities.
>   * @cpunum: CPU from which to get capabilities info.
> @@ -1365,6 +1378,60 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
>  }
>  EXPORT_SYMBOL_GPL(cppc_get_perf_ctrs);
>  
> +/*
> + * Set Energy Performance Preference Register value through
> + * Performance Controls Interface
> + */
> +int cppc_set_epp_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls, bool enable)
> +{
> +	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
> +	struct cpc_register_resource *epp_set_reg;
> +	struct cpc_register_resource *auto_sel_reg;
> +	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
> +	struct cppc_pcc_data *pcc_ss_data = NULL;
> +	int ret;
> +
> +	if (!cpc_desc) {
> +		pr_debug("No CPC descriptor for CPU:%d\n", cpu);
> +		return -ENODEV;
> +	}
> +
> +	auto_sel_reg = &cpc_desc->cpc_regs[AUTO_SEL_ENABLE];
> +	epp_set_reg = &cpc_desc->cpc_regs[ENERGY_PERF];
> +
> +	if (CPC_IN_PCC(epp_set_reg) || CPC_IN_PCC(auto_sel_reg)) {
> +		if (pcc_ss_id < 0) {
> +			pr_debug("Invalid pcc_ss_id for CPU:%d\n", cpu);
> +			return -ENODEV;
> +		}
> +
> +		if (CPC_SUPPORTED(auto_sel_reg)) {
> +			ret = cpc_write(cpu, auto_sel_reg, enable);
> +			if (ret)
> +				return ret;
> +		}
> +
> +		if (CPC_SUPPORTED(epp_set_reg)) {
> +			ret = cpc_write(cpu, epp_set_reg, perf_ctrls->energy_perf);
> +			if (ret)
> +				return ret;
> +		}
> +
> +		pcc_ss_data = pcc_data[pcc_ss_id];
> +
> +		down_write(&pcc_ss_data->pcc_lock);
> +		/* after writing CPC, transfer the ownership of PCC to platform */
> +		ret = send_pcc_cmd(pcc_ss_id, CMD_WRITE);
> +		up_write(&pcc_ss_data->pcc_lock);
> +	} else {
> +		ret = -ENOTSUPP;
> +		pr_debug("_CPC in PCC is not supported\n");
> +	}
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(cppc_set_epp_perf);
> +
>  /**
>   * cppc_set_enable - Set to enable CPPC on the processor by writing the
>   * Continuous Performance Control package EnableRegister field.
> diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h
> index c5614444031f..6b487a5bd638 100644
> --- a/include/acpi/cppc_acpi.h
> +++ b/include/acpi/cppc_acpi.h
> @@ -108,12 +108,14 @@ struct cppc_perf_caps {
>  	u32 lowest_nonlinear_perf;
>  	u32 lowest_freq;
>  	u32 nominal_freq;
> +	u32 energy_perf;
>  };
>  
>  struct cppc_perf_ctrls {
>  	u32 max_perf;
>  	u32 min_perf;
>  	u32 desired_perf;
> +	u32 energy_perf;
>  };
>  
>  struct cppc_perf_fb_ctrs {
> @@ -149,6 +151,8 @@ extern bool cpc_ffh_supported(void);
>  extern bool cpc_supported_by_cpu(void);
>  extern int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val);
>  extern int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val);
> +extern int cppc_get_epp_perf(int cpunum, u64 *epp_perf);
> +extern int cppc_set_epp_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls, bool enable);
>  #else /* !CONFIG_ACPI_CPPC_LIB */
>  static inline int cppc_get_desired_perf(int cpunum, u64 *desired_perf)
>  {
> @@ -202,6 +206,14 @@ static inline int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
>  {
>  	return -ENOTSUPP;
>  }
> +static inline int cppc_set_epp_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls, bool enable)
> +{
> +	return -ENOTSUPP;
> +}
> +static inline int cppc_get_epp_perf(int cpunum, u64 *epp_perf)
> +{
> +	return -ENOTSUPP;
> +}
>  #endif /* !CONFIG_ACPI_CPPC_LIB */
>  
>  #endif /* _CPPC_ACPI_H*/

-- 
Thanks & Regards,
Wyes