Re: [PATCH v6 1/9] cpufreq: CPPC: Add generic helpers for sysfs show/store

[Sumit Gupta <sumitg@nvidia.com>]

On 27/01/26 21:54, Rafael J. Wysocki wrote:
> External email: Use caution opening links or attachments
>
>
> On Tue, Jan 20, 2026 at 3:57 PM Sumit Gupta <sumitg@nvidia.com> wrote:
>> Add generic helper functions for u64 sysfs attributes that follow the
>> common pattern of calling CPPC get/set APIs:
>> - cppc_cpufreq_sysfs_show_u64(): reads value and handles -EOPNOTSUPP
>> - cppc_cpufreq_sysfs_store_u64(): parses input and calls set function
>>
>> Add CPPC_CPUFREQ_ATTR_RW_U64() macro to generate show/store functions
>> using these helpers, reducing boilerplate for simple attributes.
>>
>> Convert auto_act_window and energy_performance_preference_val to use
>> the new macro.
>>
>> No functional changes.
>>
>> Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
>> ---
>>   drivers/cpufreq/cppc_cpufreq.c | 69 ++++++++++++----------------------
>>   1 file changed, 25 insertions(+), 44 deletions(-)
>>
>> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
>> index 36e8a75a37f1..c95dcd7719c3 100644
>> --- a/drivers/cpufreq/cppc_cpufreq.c
>> +++ b/drivers/cpufreq/cppc_cpufreq.c
>> @@ -863,73 +863,54 @@ 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)
>> -{
>> -       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);
>> +#define CPPC_CPUFREQ_ATTR_RW_U64(_name, _get_func, _set_func)          \
>> +static ssize_t show_##_name(struct cpufreq_policy *policy, char *buf)  \
>> +{                                                                      \
>> +       return cppc_cpufreq_sysfs_show_u64(policy->cpu, _get_func, buf);\
>> +}                                                                      \
>> +static ssize_t store_##_name(struct cpufreq_policy *policy,            \
>> +                            const char *buf, size_t count)             \
>> +{                                                                      \
>> +       return cppc_cpufreq_sysfs_store_u64(policy->cpu, _set_func,     \
>> +                                           buf, count);                \
>>   }
>>
>> -static ssize_t store_energy_performance_preference_val(struct cpufreq_policy *policy,
>> -                                                      const char *buf, size_t count)
>> -{
>> -       u64 val;
>> -       int ret;
>> +CPPC_CPUFREQ_ATTR_RW_U64(auto_act_window, cppc_get_auto_act_window,
>> +                        cppc_set_auto_act_window)
>>
>> -       ret = kstrtou64(buf, 0, &val);
>> -       if (ret)
>> -               return ret;
>> -
>> -       ret = cppc_set_epp(policy->cpu, val);
>> -       if (ret)
>> -               return ret;
>> -
>> -       return count;
>> -}
>> +CPPC_CPUFREQ_ATTR_RW_U64(energy_performance_preference_val,
>> +                        cppc_get_epp_perf, cppc_set_epp)
>>
>>   cpufreq_freq_attr_ro(freqdomain_cpus);
>>   cpufreq_freq_attr_rw(auto_select);
>> --
> It looks like this patch could be applied independently of the other
> patches in the series.
>
> Do you want me to do so?

Yes, this patch is independent and can be applied.

Thank you,
Sumit Gupta