RE: [PATCH v9 3/8] cpufreq: amd-pstate: Unify computation of {max,min,nominal,lowest_nonlinear}_freq

[Meng, Li (Jassmine)]

[AMD Official Use Only - General]

> -----Original Message-----
> From: Yuan, Perry <Perry.Yuan@xxxxxxx>
> Sent: Tuesday, March 19, 2024 4:29 PM
> To: rafael.j.wysocki@xxxxxxxxx; Limonciello, Mario
> <Mario.Limonciello@xxxxxxx>; viresh.kumar@xxxxxxxxxx; Shenoy, Gautham
> Ranjal <gautham.shenoy@xxxxxxx>; Petkov, Borislav
> <Borislav.Petkov@xxxxxxx>; Huang, Ray <Ray.Huang@xxxxxxx>
> Cc: Deucher, Alexander <Alexander.Deucher@xxxxxxx>; Huang, Shimmer
> <Shimmer.Huang@xxxxxxx>; oleksandr@xxxxxxxxxxxxxx; Du, Xiaojian
> <Xiaojian.Du@xxxxxxx>; Meng, Li (Jassmine) <Li.Meng@xxxxxxx>; linux-
> pm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: [PATCH v9 3/8] cpufreq: amd-pstate: Unify computation of
> {max,min,nominal,lowest_nonlinear}_freq
>
> 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.
>
> Co-developed-by: Gautham R. Shenoy <gautham.shenoy@xxxxxxx>
> Signed-off-by: Gautham R. Shenoy <gautham.shenoy@xxxxxxx>
> Signed-off-by: Perry Yuan <perry.yuan@xxxxxxx>
> ---
>  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
[Meng, Li (Jassmine)]
Reviewed-by: Li Meng < li.meng@xxxxxxx>