Re: [PATCH v2] cpufreq: CPPC: Enable boost by default when supported

[Pengjie Zhang]

+cc Christian Loehle

On 10/22/2026 3:59 PM, Pengjie Zhang wrote:
> The CPPC driver leaves boost disabled by default when Highest Performance
> exceeds Nominal Performance. Userspace must explicitly enable boost
> before governors can use the full advertised performance range.
>
> Enable boost by default when at least one possible CPU reports support,
> while users who prefer to stay within the sustained nominal limit can
> still disable it via the boost knob without determining scaling_max_freq
> for each policy.
>
> Check the performance capabilities before registering the driver so that
> the cpufreq core enables boost for each policy that supports it.
>
> Signed-off-by: Pengjie Zhang <zhangpengjie2@xxxxxxxxxx>
> ---
> Changes in v2:
> - Drop "even" and clarify the commit message (Christian).
> - Link to v1: https://lore.kernel.org/all/20261015015812.867988-1-zhangpengjie2@xxxxxxxxxx/
>
>   drivers/cpufreq/cppc_cpufreq.c | 20 ++++++++++++++++++++
>   1 file changed, 20 insertions(+)
>
> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
> index 80893844353c..0a4255a36f60 100644
> --- a/drivers/cpufreq/cppc_cpufreq.c
> +++ b/drivers/cpufreq/cppc_cpufreq.c
> @@ -1052,6 +1052,25 @@ static struct cpufreq_driver cppc_cpufreq_driver = {
>   	.name = "cppc_cpufreq",
>   };
>   
> +static void __init cppc_cpufreq_default_boost_init(void)
> +{
> +	struct cppc_perf_caps caps;
> +	bool enable = false;
> +	int cpu;
> +
> +	for_each_possible_cpu(cpu) {
> +		if (cppc_get_perf_caps(cpu, &caps))
> +			continue;
> +
> +		if (caps.highest_perf > caps.nominal_perf) {
> +			enable = true;
> +			break;
> +		}
> +	}
> +
> +	cppc_cpufreq_driver.boost_enabled = enable;
> +}
> +
>   static int __init cppc_cpufreq_init(void)
>   {
>   	int ret;
> @@ -1061,6 +1080,7 @@ static int __init cppc_cpufreq_init(void)
>   
>   	cppc_freq_invariance_init();
>   	populate_efficiency_class();
> +	cppc_cpufreq_default_boost_init();
>   
>   	ret = cpufreq_register_driver(&cppc_cpufreq_driver);
>   	if (ret)