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Date: Mon, 19 Dec 2022 15:09:32 -0600
From: "Limonciello, Mario" <mario.limonciello@....com>
To: Perry Yuan <perry.yuan@....com>, rafael.j.wysocki@...el.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, wyes.karny@....com,
linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 01/13] ACPI: CPPC: Add AMD pstate energy performance
preference cppc control
For this patch there's a few small nits you should fix for v9.
With those fixed:
Reviewed-by: Mario Limonciello <mario.limonciello@....com>
On 12/19/2022 00:40, 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
Missing a period here at end of the sentence.
>
> 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@....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;
> -
> 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);
> +
> /**
> * 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;
AFAICT, you don't actually ever return -EINVAL in this function.
I think you should just avoid initializing this variable.
> +
> + 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");
Would it perhaps be useful to note the cpu # for this message?
> + 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*/
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