Re: [PATCH v2] cpufreq: cppc: Clamp default minimum limit to lowest_nonlinear_perf

[Viresh Kumar]

Added few more people

I think we should updated MAINTAINERS with a list of reviewers or maintainers
for the CPPC driver. Who all want to be part of the reviewers list ?

On 03-03-26, 20:03, zhangpengjie (A) wrote:
> Just a gentle ping on this patch.
> Thanks, Pengjie
> 
> On 2/13/2026 6:06 PM, Pengjie Zhang wrote:
> > The ACPI spec defines 'lowest_nonlinear_perf' as the threshold for
> > linear performance scaling. Performance levels below this threshold
> > are typically inefficient and should not be used by default.
> > 
> > Currently, the QoS minimum request is initialized to 0. This defaults
> > the performance floor to the absolute "Lowest Performance" state
> > instead of "lowest_nonlinear_perf", allowing the CPU to operate in
> > an inefficient range unnecessarily.
> > 
> > Signed-off-by: Pengjie Zhang <zhangpengjie2@xxxxxxxxxx>
> > ---
> > Changes in v2:
> >    - Renamed the patch subject to better reflect the logic change.
> >    - Updated the commit log to clarify ACPI spec details.
> > Link to v1:https://lore.kernel.org/all/20260116094555.2978887-1-zhangpengjie2@xxxxxxxxxx/
> > ---
> >   drivers/cpufreq/cppc_cpufreq.c | 18 ++++++++++++++++--
> >   1 file changed, 16 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
> > index 7e8042efedd1..4a3031d9fcf4 100644
> > --- a/drivers/cpufreq/cppc_cpufreq.c
> > +++ b/drivers/cpufreq/cppc_cpufreq.c
> > @@ -333,9 +333,23 @@ static unsigned int cppc_cpufreq_fast_switch(struct cpufreq_policy *policy,
> >   	return target_freq;
> >   }
> > -static int cppc_verify_policy(struct cpufreq_policy_data *policy)
> > +static int cppc_verify_policy(struct cpufreq_policy_data *policy_data)
> >   {
> > -	cpufreq_verify_within_cpu_limits(policy);
> > +	if (policy_data->min == FREQ_QOS_MIN_DEFAULT_VALUE) {
> > +		struct cpufreq_policy *policy __free(put_cpufreq_policy) =
> > +					      cpufreq_cpu_get(policy_data->cpu);
> > +		struct cppc_cpudata *cpu_data;
> > +
> > +		if (!policy)
> > +			return -EINVAL;
> > +
> > +		cpu_data = policy->driver_data;
> > +		policy_data->min = cppc_perf_to_khz(&cpu_data->perf_caps,
> > +			cpu_data->perf_caps.lowest_nonlinear_perf);
> > +	}
> > +
> > +	cpufreq_verify_within_cpu_limits(policy_data);
> > +
> >   	return 0;
> >   }

-- 
viresh