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Date:   Fri, 23 Dec 2022 10:16:06 +0800
From:   Huang Rui <ray.huang@amd.com>
To:     "Yuan, Perry" <Perry.Yuan@amd.com>
Cc:     "rafael.j.wysocki@intel.com" <rafael.j.wysocki@intel.com>,
        "Limonciello, Mario" <Mario.Limonciello@amd.com>,
        "viresh.kumar@linaro.org" <viresh.kumar@linaro.org>,
        "Sharma, Deepak" <Deepak.Sharma@amd.com>,
        "Fontenot, Nathan" <Nathan.Fontenot@amd.com>,
        "Deucher, Alexander" <Alexander.Deucher@amd.com>,
        "Huang, Shimmer" <Shimmer.Huang@amd.com>,
        "Du, Xiaojian" <Xiaojian.Du@amd.com>,
        "Meng, Li (Jassmine)" <Li.Meng@amd.com>,
        "Karny, Wyes" <Wyes.Karny@amd.com>,
        "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v8 01/13] ACPI: CPPC: Add AMD pstate energy performance
 preference cppc control
Message-ID: <Y6UPZgtFvlJm3bVR@amd.com>
References: <20221219064042.661122-1-perry.yuan@amd.com>
 <20221219064042.661122-2-perry.yuan@amd.com>
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On Mon, Dec 19, 2022 at 02:40:30PM +0800, Yuan, Perry wrote:
> From: Perry Yuan <Perry.Yuan@amd.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.
> 
> Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
> ---
>  drivers/acpi/cppc_acpi.c | 76 +++++++++++++++++++++++++++++++++++++---
>  include/acpi/cppc_acpi.h | 12 +++++++
>  2 files changed, 83 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index 093675b1a1ff..81081eb899ea 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -1093,6 +1093,9 @@ static int cppc_get_perf(int cpunum, enum cppc_regs reg_idx, u64 *perf)
>  {
>  	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
>  	struct cpc_register_resource *reg;
> +	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
> +	struct cppc_pcc_data *pcc_ss_data = NULL;
> +	int ret = -EINVAL;
>  
>  	if (!cpc_desc) {
>  		pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
> @@ -1102,10 +1105,6 @@ static int cppc_get_perf(int cpunum, enum cppc_regs reg_idx, u64 *perf)
>  	reg = &cpc_desc->cpc_regs[reg_idx];
>  
>  	if (CPC_IN_PCC(reg)) {
> -		int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
> -		struct cppc_pcc_data *pcc_ss_data = NULL;
> -		int ret = 0;
> -

Do you have any specific reason to move this piece out of if-condition?

>  		if (pcc_ss_id < 0)
>  			return -EIO;
>  
> @@ -1125,7 +1124,7 @@ static int cppc_get_perf(int cpunum, enum cppc_regs reg_idx, u64 *perf)
>  
>  	cpc_read(cpunum, reg, perf);
>  
> -	return 0;
> +	return ret;
>  }
>  
>  /**
> @@ -1153,6 +1152,19 @@ 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);
> +

This function is enough to get the epp value.

Thanks,
Ray

>  /**
>   * cppc_get_perf_caps - Get a CPU's performance capabilities.
>   * @cpunum: CPU from which to get capabilities info.
> @@ -1365,6 +1377,60 @@ 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 = -EINVAL;
> +
> +	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\n");
> +			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*/
> -- 
> 2.34.1
>