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Date: Mon, 15 Apr 2024 22:54:31 +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>,
	"Shenoy, Gautham Ranjal" <gautham.shenoy@amd.com>,
	"Petkov, Borislav" <Borislav.Petkov@amd.com>,
	"Deucher, Alexander" <Alexander.Deucher@amd.com>,
	"Huang, Shimmer" <Shimmer.Huang@amd.com>,
	"oleksandr@natalenko.name" <oleksandr@natalenko.name>,
	"Du, Xiaojian" <Xiaojian.Du@amd.com>,
	"Meng, Li (Jassmine)" <Li.Meng@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 v10 3/8] cpufreq: amd-pstate: Unify computation of
 {max,min,nominal,lowest_nonlinear}_freq
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On Mon, Mar 25, 2024 at 11:03:23AM +0800, Yuan, Perry wrote:
> Currently the amd_get_{min, max, nominal, lowest_nonlinear}_freq()
> helpers computes the values of min_freq, max_freq, nominal_freq and
> lowest_nominal_freq respectively afresh from
> cppc_get_perf_caps(). This is not necessary as there are fields in
> cpudata to cache these values.
> 
> To simplify this, add a single helper function named
> amd_pstate_init_freq() which computes all these frequencies at once, and
> caches it in cpudata.
> 
> Use the cached values everywhere else in the code.
> 
> Reviewed-by: Li Meng <li.meng@amd.com>
> Tested-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@amd.com>
> Co-developed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
> Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
> Signed-off-by: Perry Yuan <perry.yuan@amd.com>

I am thinking patch 3 and 4 should be squeezed together, because they are
all refining frequencies in cpudata. But I am fine if you want to continue
keep them separately.

> ---
>  drivers/cpufreq/amd-pstate.c | 126 ++++++++++++++++-------------------
>  1 file changed, 59 insertions(+), 67 deletions(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 2015c9fcc3c9..ba1baa6733e6 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -606,74 +606,22 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
>  
>  static int amd_get_min_freq(struct amd_cpudata *cpudata)
>  {
> -	struct cppc_perf_caps cppc_perf;
> -
> -	int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> -	if (ret)
> -		return ret;
> -
> -	/* Switch to khz */
> -	return cppc_perf.lowest_freq * 1000;
> +	return READ_ONCE(cpudata->min_freq);
>  }
>  
>  static int amd_get_max_freq(struct amd_cpudata *cpudata)
>  {
> -	struct cppc_perf_caps cppc_perf;
> -	u32 max_perf, max_freq, nominal_freq, nominal_perf;
> -	u64 boost_ratio;
> -
> -	int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> -	if (ret)
> -		return ret;
> -
> -	nominal_freq = cppc_perf.nominal_freq;
> -	nominal_perf = READ_ONCE(cpudata->nominal_perf);
> -	max_perf = READ_ONCE(cpudata->highest_perf);
> -
> -	boost_ratio = div_u64(max_perf << SCHED_CAPACITY_SHIFT,
> -			      nominal_perf);
> -
> -	max_freq = nominal_freq * boost_ratio >> SCHED_CAPACITY_SHIFT;
> -
> -	/* Switch to khz */
> -	return max_freq * 1000;
> +	return READ_ONCE(cpudata->max_freq);
>  }
>  
>  static int amd_get_nominal_freq(struct amd_cpudata *cpudata)
>  {
> -	struct cppc_perf_caps cppc_perf;
> -
> -	int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> -	if (ret)
> -		return ret;
> -
> -	/* Switch to khz */
> -	return cppc_perf.nominal_freq * 1000;
> +	return READ_ONCE(cpudata->nominal_freq);
>  }
>  
>  static int amd_get_lowest_nonlinear_freq(struct amd_cpudata *cpudata)
>  {
> -	struct cppc_perf_caps cppc_perf;
> -	u32 lowest_nonlinear_freq, lowest_nonlinear_perf,
> -	    nominal_freq, nominal_perf;
> -	u64 lowest_nonlinear_ratio;
> -
> -	int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> -	if (ret)
> -		return ret;
> -
> -	nominal_freq = cppc_perf.nominal_freq;
> -	nominal_perf = READ_ONCE(cpudata->nominal_perf);
> -
> -	lowest_nonlinear_perf = cppc_perf.lowest_nonlinear_perf;
> -
> -	lowest_nonlinear_ratio = div_u64(lowest_nonlinear_perf << SCHED_CAPACITY_SHIFT,
> -					 nominal_perf);
> -
> -	lowest_nonlinear_freq = nominal_freq * lowest_nonlinear_ratio >> SCHED_CAPACITY_SHIFT;
> -
> -	/* Switch to khz */
> -	return lowest_nonlinear_freq * 1000;
> +	return READ_ONCE(cpudata->lowest_nonlinear_freq);
>  }
>  
>  static int amd_pstate_set_boost(struct cpufreq_policy *policy, int state)
> @@ -828,6 +776,53 @@ static void amd_pstate_update_limits(unsigned int cpu)
>  	mutex_unlock(&amd_pstate_driver_lock);
>  }
>  
> +/**
> + * amd_pstate_init_freq: Initialize the max_freq, min_freq,
> + *                       nominal_freq and lowest_nonlinear_freq for
> + *                       the @cpudata object.
> + *
> + *  Requires: highest_perf, lowest_perf, nominal_perf and
> + *            lowest_nonlinear_perf members of @cpudata to be
> + *            initialized.
> + *
> + *  Returns 0 on success, non-zero value on failure.
> + */
> +static int amd_pstate_init_freq(struct amd_cpudata *cpudata)
> +{
> +	int ret;
> +	u32 min_freq;
> +	u32 highest_perf, max_freq;
> +	u32 nominal_perf, nominal_freq;
> +	u32 lowest_nonlinear_perf, lowest_nonlinear_freq;
> +	u32 boost_ratio, lowest_nonlinear_ratio;
> +	struct cppc_perf_caps cppc_perf;
> +
> +
> +	ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> +	if (ret)
> +		return ret;
> +
> +	min_freq = cppc_perf.lowest_freq * 1000;
> +	nominal_freq = cppc_perf.nominal_freq * 1000;
> +	nominal_perf = READ_ONCE(cpudata->nominal_perf);
> +
> +	highest_perf = READ_ONCE(cpudata->highest_perf);
> +	boost_ratio = div_u64(highest_perf << SCHED_CAPACITY_SHIFT, nominal_perf);
> +	max_freq = nominal_freq * boost_ratio >> SCHED_CAPACITY_SHIFT;
> +
> +	lowest_nonlinear_perf = READ_ONCE(cpudata->lowest_nonlinear_perf);
> +	lowest_nonlinear_ratio = div_u64(lowest_nonlinear_perf << SCHED_CAPACITY_SHIFT,
> +					 nominal_perf);
> +	lowest_nonlinear_freq = nominal_freq * lowest_nonlinear_ratio >> SCHED_CAPACITY_SHIFT;
> +
> +	WRITE_ONCE(cpudata->min_freq, min_freq);
> +	WRITE_ONCE(cpudata->lowest_nonlinear_freq, lowest_nonlinear_freq);
> +	WRITE_ONCE(cpudata->nominal_freq, nominal_freq);
> +	WRITE_ONCE(cpudata->max_freq, max_freq);
> +
> +	return 0;
> +}
> +
>  static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
>  {
>  	int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
> @@ -855,6 +850,10 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
>  	if (ret)
>  		goto free_cpudata1;
>  
> +	ret = amd_pstate_init_freq(cpudata);
> +	if (ret)
> +		goto free_cpudata1;
> +
>  	min_freq = amd_get_min_freq(cpudata);
>  	max_freq = amd_get_max_freq(cpudata);
>  	nominal_freq = amd_get_nominal_freq(cpudata);
> @@ -896,13 +895,8 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
>  		goto free_cpudata2;
>  	}
>  
> -	/* Initial processor data capability frequencies */
> -	cpudata->max_freq = max_freq;
> -	cpudata->min_freq = min_freq;
>  	cpudata->max_limit_freq = max_freq;
>  	cpudata->min_limit_freq = min_freq;
> -	cpudata->nominal_freq = nominal_freq;
> -	cpudata->lowest_nonlinear_freq = lowest_nonlinear_freq;
>  
>  	policy->driver_data = cpudata;
>  
> @@ -1317,6 +1311,10 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
>  	if (ret)
>  		goto free_cpudata1;
>  
> +	ret = amd_pstate_init_freq(cpudata);
> +	if (ret)
> +		goto free_cpudata1;
> +
>  	min_freq = amd_get_min_freq(cpudata);
>  	max_freq = amd_get_max_freq(cpudata);
>  	nominal_freq = amd_get_nominal_freq(cpudata);
> @@ -1333,12 +1331,6 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
>  	/* It will be updated by governor */
>  	policy->cur = policy->cpuinfo.min_freq;
>  
> -	/* Initial processor data capability frequencies */
> -	cpudata->max_freq = max_freq;
> -	cpudata->min_freq = min_freq;
> -	cpudata->nominal_freq = nominal_freq;
> -	cpudata->lowest_nonlinear_freq = lowest_nonlinear_freq;
> -
>  	policy->driver_data = cpudata;
>  
>  	cpudata->epp_cached = amd_pstate_get_epp(cpudata, 0);
> -- 
> 2.34.1
>