linux-kernel - Re: [PATCH v5 01/11] cpufreq: CPPC: Add generic helpers for sysfs show/store

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Message-ID: <bd2e287b-481e-48d8-8bfa-73dbf8758220@nvidia.com>
Date: Thu, 8 Jan 2026 19:01:49 +0530
From: Sumit Gupta <sumitg@...dia.com>
To: "zhenglifeng (A)" <zhenglifeng1@...wei.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, sumitg@...dia.com
Subject: Re: [PATCH v5 01/11] cpufreq: CPPC: Add generic helpers for sysfs
 show/store


On 25/12/25 09:11, zhenglifeng (A) wrote:
> External email: Use caution opening links or attachments
>
>
> On 2025/12/23 20:12, Sumit Gupta wrote:
>> Add generic show/store helper functions for u64 sysfs attributes:
>> - cppc_cpufreq_sysfs_show_u64()
>> - cppc_cpufreq_sysfs_store_u64()
>>
>> Refactor auto_act_window and energy_performance_preference_val
>> attributes to use these helpers, eliminating code duplication.
> How about adding a macro to generate show_xxx and store_xxx in one line?
>
> Just a suggestion.

will add macro in v6.

Thank you,
Sumit Gupta


>> No functional changes.
>>
>> Signed-off-by: Sumit Gupta <sumitg@...dia.com>
>> ---
>>   drivers/cpufreq/cppc_cpufreq.c | 71 +++++++++++++++-------------------
>>   1 file changed, 31 insertions(+), 40 deletions(-)
>>
>> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
>> index 9eac77c4f294..7c26ce554e29 100644
>> --- a/drivers/cpufreq/cppc_cpufreq.c
>> +++ b/drivers/cpufreq/cppc_cpufreq.c
>> @@ -831,72 +831,63 @@ static ssize_t store_auto_select(struct cpufreq_policy *policy,
>>        return count;
>>   }
>>
>> -static ssize_t show_auto_act_window(struct cpufreq_policy *policy, char *buf)
>> +static ssize_t cppc_cpufreq_sysfs_show_u64(unsigned int cpu,
>> +                                        int (*get_func)(int, u64 *),
>> +                                        char *buf)
>>   {
>>        u64 val;
>> -     int ret;
>> -
>> -     ret = cppc_get_auto_act_window(policy->cpu, &val);
>> +     int ret = get_func((int)cpu, &val);
>>
>> -     /* show "<unsupported>" when this register is not supported by cpc */
>>        if (ret == -EOPNOTSUPP)
>>                return sysfs_emit(buf, "<unsupported>\n");
>> -
>>        if (ret)
>>                return ret;
>>
>>        return sysfs_emit(buf, "%llu\n", val);
>>   }
>>
>> -static ssize_t store_auto_act_window(struct cpufreq_policy *policy,
>> -                                  const char *buf, size_t count)
>> +static ssize_t cppc_cpufreq_sysfs_store_u64(unsigned int cpu,
>> +                                         int (*set_func)(int, u64),
>> +                                         const char *buf, size_t count)
>>   {
>> -     u64 usec;
>> +     u64 val;
>>        int ret;
>>
>> -     ret = kstrtou64(buf, 0, &usec);
>> +     ret = kstrtou64(buf, 0, &val);
>>        if (ret)
>>                return ret;
>>
>> -     ret = cppc_set_auto_act_window(policy->cpu, usec);
>> -     if (ret)
>> -             return ret;
>> +     ret = set_func((int)cpu, val);
>>
>> -     return count;
>> +     return ret ? ret : count;
>>   }
>>
>> -static ssize_t show_energy_performance_preference_val(struct cpufreq_policy *policy, char *buf)
>> +static ssize_t show_auto_act_window(struct cpufreq_policy *policy, char *buf)
>>   {
>> -     u64 val;
>> -     int ret;
>> -
>> -     ret = cppc_get_epp_perf(policy->cpu, &val);
>> -
>> -     /* show "<unsupported>" when this register is not supported by cpc */
>> -     if (ret == -EOPNOTSUPP)
>> -             return sysfs_emit(buf, "<unsupported>\n");
>> -
>> -     if (ret)
>> -             return ret;
>> -
>> -     return sysfs_emit(buf, "%llu\n", val);
>> +     return cppc_cpufreq_sysfs_show_u64(policy->cpu,
>> +                                        cppc_get_auto_act_window, buf);
>>   }
>>
>> -static ssize_t store_energy_performance_preference_val(struct cpufreq_policy *policy,
>> -                                                    const char *buf, size_t count)
>> +static ssize_t store_auto_act_window(struct cpufreq_policy *policy,
>> +                                  const char *buf, size_t count)
>>   {
>> -     u64 val;
>> -     int ret;
>> -
>> -     ret = kstrtou64(buf, 0, &val);
>> -     if (ret)
>> -             return ret;
>> +     return cppc_cpufreq_sysfs_store_u64(policy->cpu,
>> +                                         cppc_set_auto_act_window,
>> +                                         buf, count);
>> +}
>>
>> -     ret = cppc_set_epp(policy->cpu, val);
>> -     if (ret)
>> -             return ret;
>> +static ssize_t
>> +show_energy_performance_preference_val(struct cpufreq_policy *policy, char *buf)
>> +{
>> +     return cppc_cpufreq_sysfs_show_u64(policy->cpu, cppc_get_epp_perf, buf);
>> +}
>>
>> -     return count;
>> +static ssize_t
>> +store_energy_performance_preference_val(struct cpufreq_policy *policy,
>> +                                     const char *buf, size_t count)
>> +{
>> +     return cppc_cpufreq_sysfs_store_u64(policy->cpu, cppc_set_epp,
>> +                                         buf, count);
>>   }
>>
>>   cpufreq_freq_attr_ro(freqdomain_cpus);