RE: [PATCH v8 01/13] ACPI: CPPC: Add AMD pstate energy performance preference cppc control

[Yuan, Perry]

[AMD Official Use Only - General]



> -----Original Message-----
> From: Huang, Ray <Ray.Huang@xxxxxxx>
> Sent: Friday, December 23, 2022 10:16 AM
> To: Yuan, Perry <Perry.Yuan@xxxxxxx>
> Cc: rafael.j.wysocki@xxxxxxxxx; Limonciello, Mario
> <Mario.Limonciello@xxxxxxx>; viresh.kumar@xxxxxxxxxx; Sharma, Deepak
> <Deepak.Sharma@xxxxxxx>; Fontenot, Nathan
> <Nathan.Fontenot@xxxxxxx>; Deucher, Alexander
> <Alexander.Deucher@xxxxxxx>; Huang, Shimmer
> <Shimmer.Huang@xxxxxxx>; Du, Xiaojian <Xiaojian.Du@xxxxxxx>; Meng,
> Li (Jassmine) <Li.Meng@xxxxxxx>; Karny, Wyes <Wyes.Karny@xxxxxxx>;
> linux-pm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v8 01/13] ACPI: CPPC: Add AMD pstate energy
> performance preference cppc control
> 
> On Mon, Dec 19, 2022 at 02:40:30PM +0800, Yuan, Perry wrote:
> > From: Perry Yuan <Perry.Yuan@xxxxxxx>
> >
> > 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@xxxxxxx>
> > ---
> >  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?

Move the declaration ahead of the If conditions like other functions did.
It looks more reasonable and no functions impact. 

Perry. 

> 
> >  		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
> >