linux-kernel - Re: [PATCH v5 08/11] cpufreq: CPPC: sync policy limits when updating min/max

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Message-ID: <9ea62a14-46a1-4238-97ed-aeabf9f3ab77@huawei.com>
Date: Thu, 25 Dec 2025 21:56:46 +0800
From: "zhenglifeng (A)" <zhenglifeng1@...wei.com>
To: Sumit Gupta <sumitg@...dia.com>, <rafael@...nel.org>,
	<viresh.kumar@...aro.org>, <lenb@...nel.org>, <robert.moore@...el.com>,
	<corbet@....net>, <pierre.gondois@....com>, <rdunlap@...radead.org>,
	<ray.huang@....com>, <gautham.shenoy@....com>, <mario.limonciello@....com>,
	<perry.yuan@....com>, <ionela.voinescu@....com>, <zhanjie9@...ilicon.com>,
	<linux-pm@...r.kernel.org>, <linux-acpi@...r.kernel.org>,
	<linux-doc@...r.kernel.org>, <acpica-devel@...ts.linux.dev>,
	<linux-kernel@...r.kernel.org>
CC: <linux-tegra@...r.kernel.org>, <treding@...dia.com>,
	<jonathanh@...dia.com>, <vsethi@...dia.com>, <ksitaraman@...dia.com>,
	<sanjayc@...dia.com>, <nhartman@...dia.com>, <bbasu@...dia.com>
Subject: Re: [PATCH v5 08/11] cpufreq: CPPC: sync policy limits when updating
 min/max_perf

On 2025/12/23 20:13, Sumit Gupta wrote:
> When min_perf or max_perf is updated via sysfs in autonomous mode, the
> policy frequency limits should also be updated to reflect the new
> performance bounds.
> 
> Add @update_policy parameter to cppc_cpufreq_set_mperf_limit() to
> control whether policy constraints are synced with HW registers.
> The policy is updated only when autonomous selection is enabled to
> keep SW limits in sync with HW.
> 
> This ensures that scaling_min_freq and scaling_max_freq values remain
> consistent with the actual min/max_perf register values when operating
> in autonomous mode.
> 
> Signed-off-by: Sumit Gupta <sumitg@...dia.com>
> ---
>  drivers/cpufreq/cppc_cpufreq.c | 35 ++++++++++++++++++++++++++--------
>  1 file changed, 27 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
> index 1f8825006940..0202c7b823e6 100644
> --- a/drivers/cpufreq/cppc_cpufreq.c
> +++ b/drivers/cpufreq/cppc_cpufreq.c
> @@ -544,14 +544,20 @@ static void populate_efficiency_class(void)
>   * cppc_cpufreq_set_mperf_limit - Set min/max performance limit
>   * @policy: cpufreq policy
>   * @val: performance value to set
> + * @update_policy: whether to update policy constraints
>   * @is_min: true for min_perf, false for max_perf
> + *
> + * When @update_policy is true, updates cpufreq policy frequency limits.
> + * @update_policy is false during cpu_init when policy isn't fully set up.
>   */
>  static int cppc_cpufreq_set_mperf_limit(struct cpufreq_policy *policy, u64 val,
> -					bool is_min)
> +					bool update_policy, bool is_min)
>  {
>  	struct cppc_cpudata *cpu_data = policy->driver_data;
>  	struct cppc_perf_caps *caps = &cpu_data->perf_caps;
>  	unsigned int cpu = policy->cpu;
> +	struct freq_qos_request *req;
> +	unsigned int freq;
>  	u32 perf;
>  	int ret;
>  
> @@ -571,15 +577,26 @@ static int cppc_cpufreq_set_mperf_limit(struct cpufreq_policy *policy, u64 val,
>  	else
>  		cpu_data->perf_ctrls.max_perf = perf;
>  
> +	if (update_policy) {
> +		freq = cppc_perf_to_khz(caps, perf);
> +		req = is_min ? policy->min_freq_req : policy->max_freq_req;
> +
> +		ret = freq_qos_update_request(req, freq);
> +		if (ret < 0) {
> +			pr_warn("Failed to update %s_freq constraint for CPU%d: %d\n",
> +				is_min ? "min" : "max", cpu, ret);
> +			return ret;
> +		}
> +	}
> +

OK. Now I see the necessity of extracting this function. But why not use
freq_khz as a input parameter and convert it to perf in this funciton,
since you need the freq here?

>  	return 0;
>  }
>  
> -#define cppc_cpufreq_set_min_perf(policy, val) \
> -	cppc_cpufreq_set_mperf_limit(policy, val, true)
> -
> -#define cppc_cpufreq_set_max_perf(policy, val) \
> -	cppc_cpufreq_set_mperf_limit(policy, val, false)
> +#define cppc_cpufreq_set_min_perf(policy, val, update_policy) \
> +	cppc_cpufreq_set_mperf_limit(policy, val, update_policy, true)
>  
> +#define cppc_cpufreq_set_max_perf(policy, val, update_policy) \
> +	cppc_cpufreq_set_mperf_limit(policy, val, update_policy, false)
>  static struct cppc_cpudata *cppc_cpufreq_get_cpu_data(unsigned int cpu)
>  {
>  	struct cppc_cpudata *cpu_data;
> @@ -988,7 +1005,8 @@ static ssize_t store_min_perf(struct cpufreq_policy *policy, const char *buf,
>  	perf = cppc_khz_to_perf(&cpu_data->perf_caps, freq_khz);
>  
>  	guard(mutex)(&cppc_cpufreq_update_autosel_config_lock);
> -	ret = cppc_cpufreq_set_min_perf(policy, perf);
> +	ret = cppc_cpufreq_set_min_perf(policy, perf,
> +					cpu_data->perf_ctrls.auto_sel);
>  	if (ret)
>  		return ret;
>  
> @@ -1045,7 +1063,8 @@ static ssize_t store_max_perf(struct cpufreq_policy *policy, const char *buf,
>  	perf = cppc_khz_to_perf(&cpu_data->perf_caps, freq_khz);
>  
>  	guard(mutex)(&cppc_cpufreq_update_autosel_config_lock);
> -	ret = cppc_cpufreq_set_max_perf(policy, perf);
> +	ret = cppc_cpufreq_set_max_perf(policy, perf,
> +					cpu_data->perf_ctrls.auto_sel);
>  	if (ret)
>  		return ret;
>