RE: [PATCH 1/4] cpufreq/amd-pstate: Use nominal perf for limits when boost is disabled

[Yuan, Perry]

[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Limonciello, Mario <Mario.Limonciello@xxxxxxx>
> Sent: Sunday, October 13, 2024 1:45 AM
> To: Shenoy, Gautham Ranjal <gautham.shenoy@xxxxxxx>
> Cc: Yuan, Perry <Perry.Yuan@xxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; linux-
> pm@xxxxxxxxxxxxxxx; Ugwekar, Dhananjay <Dhananjay.Ugwekar@xxxxxxx>;
> Limonciello, Mario <Mario.Limonciello@xxxxxxx>; Peter Jung
> <ptr1337@xxxxxxxxxxx>
> Subject: [PATCH 1/4] cpufreq/amd-pstate: Use nominal perf for limits when boost is
> disabled
>
> When boost has been disabled the limit for perf should be nominal perf not the
> highest perf.  Using the latter to do calculations will lead to incorrect values that are
> still above nominal.
>
> Fixes: ad4caad58d91 ("cpufreq: amd-pstate: Merge amd_pstate_highest_perf_set()
> into amd_get_boost_ratio_numerator()")
> Reported-by: Peter Jung <ptr1337@xxxxxxxxxxx>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219348
> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> ---
>  drivers/cpufreq/amd-pstate.c | 20 ++++++++++++++------
>  1 file changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c index
> 30415c30d8b4..dfa9a146769b 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -536,11 +536,16 @@ static int amd_pstate_verify(struct cpufreq_policy_data
> *policy)
>
>  static int amd_pstate_update_min_max_limit(struct cpufreq_policy *policy)  {
> -     u32 max_limit_perf, min_limit_perf, lowest_perf;
> +     u32 max_limit_perf, min_limit_perf, lowest_perf, max_perf;
>       struct amd_cpudata *cpudata = policy->driver_data;
>
> -     max_limit_perf = div_u64(policy->max * cpudata->highest_perf, cpudata-
> >max_freq);
> -     min_limit_perf = div_u64(policy->min * cpudata->highest_perf, cpudata-
> >max_freq);
> +     if (cpudata->boost_supported && !policy->boost_enabled)
> +             max_perf = READ_ONCE(cpudata->nominal_perf);
> +     else
> +             max_perf = READ_ONCE(cpudata->highest_perf);
> +
> +     max_limit_perf = div_u64(policy->max * max_perf, policy-
> >cpuinfo.max_freq);
> +     min_limit_perf = div_u64(policy->min * max_perf,
> +policy->cpuinfo.max_freq);
>
>       lowest_perf = READ_ONCE(cpudata->lowest_perf);
>       if (min_limit_perf < lowest_perf)
> @@ -1506,10 +1511,13 @@ static int amd_pstate_epp_update_limit(struct
> cpufreq_policy *policy)
>       u64 value;
>       s16 epp;
>
> -     max_perf = READ_ONCE(cpudata->highest_perf);
> +     if (cpudata->boost_supported && !policy->boost_enabled)
> +             max_perf = READ_ONCE(cpudata->nominal_perf);
> +     else
> +             max_perf = READ_ONCE(cpudata->highest_perf);
>       min_perf = READ_ONCE(cpudata->lowest_perf);
> -     max_limit_perf = div_u64(policy->max * cpudata->highest_perf, cpudata-
> >max_freq);
> -     min_limit_perf = div_u64(policy->min * cpudata->highest_perf, cpudata-
> >max_freq);
> +     max_limit_perf = div_u64(policy->max * max_perf, policy-
> >cpuinfo.max_freq);
> +     min_limit_perf = div_u64(policy->min * max_perf,
> +policy->cpuinfo.max_freq);
>
>       if (min_limit_perf < min_perf)
>               min_limit_perf = min_perf;
> --
> 2.43.0

LGTM, thanks for the fix.

Reviewed-by: Perry Yuan <perry.yuan@xxxxxxx>