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Date:   Wed, 18 Jan 2023 12:04:50 +0530
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Subject: Re: [PATCH v10 08/12] cpufreq: amd-pstate: add driver working mode
 switch support
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To:     Huang Rui <ray.huang@amd.com>, "Yuan, Perry" <Perry.Yuan@amd.com>
Cc:     "rafael.j.wysocki@intel.com" <rafael.j.wysocki@intel.com>,
        "Limonciello, Mario" <Mario.Limonciello@amd.com>,
        "viresh.kumar@linaro.org" <viresh.kumar@linaro.org>,
        "Sharma, Deepak" <Deepak.Sharma@amd.com>,
        "Fontenot, Nathan" <Nathan.Fontenot@amd.com>,
        "Deucher, Alexander" <Alexander.Deucher@amd.com>,
        "Huang, Shimmer" <Shimmer.Huang@amd.com>,
        "Du, Xiaojian" <Xiaojian.Du@amd.com>,
        "Meng, Li (Jassmine)" <Li.Meng@amd.com>,
        "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <20230106061420.95715-1-perry.yuan@amd.com>
 <20230106061420.95715-9-perry.yuan@amd.com> <Y8apIMZ3b+dLrpA7@amd.com>
From:   Wyes Karny <wyes.karny@amd.com>
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Hi Ray, Perry,

On 1/17/2023 7:26 PM, Huang Rui wrote:
> On Fri, Jan 06, 2023 at 02:14:16PM +0800, Yuan, Perry wrote:
>> From: Perry Yuan <Perry.Yuan@amd.com>
>>
>> While amd-pstate driver was loaded with specific driver mode, it will
>> need to check which mode is enabled for the pstate driver,add this sysfs
>> entry to show the current status
>>
>> $ cat /sys/devices/system/cpu/amd-pstate/status
>> active
>>
>> Meanwhile, user can switch the pstate driver mode with writing mode
>> string to sysfs entry as below.
>>
>> Enable passive mode:
>> $ sudo bash -c "echo passive >  /sys/devices/system/cpu/amd-pstate/status"
>>
>> Enable active mode (EPP driver mode):
>> $ sudo bash -c "echo active > /sys/devices/system/cpu/amd-pstate/status"
>>
>> Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
>> Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
> 
> Patch is Acked-by: Huang Rui <ray.huang@amd.com>
> 
> Wyes, may we have a ack or any comment from you of this patch, as you are
> working on the new guided autonomous mode?

This looks good to me.

Reviewed-by: Wyes Karny <wyes.karny@amd.com>

> 
> Thanks,
> Ray
> 
>> ---
>>  drivers/cpufreq/amd-pstate.c | 118 +++++++++++++++++++++++++++++++++++
>>  1 file changed, 118 insertions(+)
>>
>> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
>> index 2c8b126cec5a..d3f4cdd803f3 100644
>> --- a/drivers/cpufreq/amd-pstate.c
>> +++ b/drivers/cpufreq/amd-pstate.c
>> @@ -63,6 +63,7 @@ static struct cpufreq_driver *current_pstate_driver;
>>  static struct cpufreq_driver amd_pstate_driver;
>>  static struct cpufreq_driver amd_pstate_epp_driver;
>>  static int cppc_state = AMD_PSTATE_DISABLE;
>> +struct kobject *amd_pstate_kobj;
>>  
>>  static inline int get_mode_idx_from_str(const char *str, size_t size)
>>  {
>> @@ -631,6 +632,8 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
>>  	policy->driver_data = cpudata;
>>  
>>  	amd_pstate_boost_init(cpudata);
>> +	if (!current_pstate_driver->adjust_perf)
>> +		current_pstate_driver->adjust_perf = amd_pstate_adjust_perf;
>>  
>>  	return 0;
>>  
>> @@ -771,12 +774,99 @@ static ssize_t show_energy_performance_preference(
>>  	return sysfs_emit(buf, "%s\n", energy_perf_strings[preference]);
>>  }
>>  
>> +static ssize_t amd_pstate_show_status(char *buf)
>> +{
>> +	if (!current_pstate_driver)
>> +		return sysfs_emit(buf, "disable\n");
>> +
>> +	return sysfs_emit(buf, "%s\n", amd_pstate_mode_string[cppc_state]);
>> +}
>> +
>> +static void amd_pstate_driver_cleanup(void)
>> +{
>> +	current_pstate_driver = NULL;
>> +}
>> +
>> +static int amd_pstate_update_status(const char *buf, size_t size)
>> +{
>> +	int ret;
>> +	int mode_idx;
>> +
>> +	if (size > 7 || size < 6)
>> +		return -EINVAL;
>> +	mode_idx = get_mode_idx_from_str(buf, size);
>> +
>> +	switch(mode_idx) {
>> +	case AMD_PSTATE_DISABLE:
>> +		if (!current_pstate_driver)
>> +			return -EINVAL;
>> +		if (cppc_state == AMD_PSTATE_ACTIVE)
>> +			return -EBUSY;
>> +		ret = cpufreq_unregister_driver(current_pstate_driver);
>> +		amd_pstate_driver_cleanup();
>> +		break;
>> +	case AMD_PSTATE_PASSIVE:
>> +		if (current_pstate_driver) {
>> +			if (current_pstate_driver == &amd_pstate_driver)
>> +				return 0;
>> +			cpufreq_unregister_driver(current_pstate_driver);
>> +			cppc_state = AMD_PSTATE_PASSIVE;
>> +			current_pstate_driver = &amd_pstate_driver;
>> +		}
>> +
>> +		ret = cpufreq_register_driver(current_pstate_driver);
>> +		break;
>> +	case AMD_PSTATE_ACTIVE:
>> +		if (current_pstate_driver) {
>> +			if (current_pstate_driver == &amd_pstate_epp_driver)
>> +				return 0;
>> +			cpufreq_unregister_driver(current_pstate_driver);
>> +			current_pstate_driver = &amd_pstate_epp_driver;
>> +			cppc_state = AMD_PSTATE_ACTIVE;
>> +		}
>> +
>> +		ret = cpufreq_register_driver(current_pstate_driver);
>> +		break;
>> +	default:
>> +		ret = -EINVAL;
>> +		break;
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +static ssize_t show_status(struct kobject *kobj,
>> +			   struct kobj_attribute *attr, char *buf)
>> +{
>> +	ssize_t ret;
>> +
>> +	mutex_lock(&amd_pstate_driver_lock);
>> +	ret = amd_pstate_show_status(buf);
>> +	mutex_unlock(&amd_pstate_driver_lock);
>> +
>> +	return ret;
>> +}
>> +
>> +static ssize_t store_status(struct kobject *a, struct kobj_attribute *b,
>> +			    const char *buf, size_t count)
>> +{
>> +	char *p = memchr(buf, '\n', count);
>> +	int ret;
>> +
>> +	mutex_lock(&amd_pstate_driver_lock);
>> +	ret = amd_pstate_update_status(buf, p ? p - buf : count);
>> +	mutex_unlock(&amd_pstate_driver_lock);
>> +
>> +	return ret < 0 ? ret : count;
>> +}
>> +
>>  cpufreq_freq_attr_ro(amd_pstate_max_freq);
>>  cpufreq_freq_attr_ro(amd_pstate_lowest_nonlinear_freq);
>>  
>>  cpufreq_freq_attr_ro(amd_pstate_highest_perf);
>>  cpufreq_freq_attr_rw(energy_performance_preference);
>>  cpufreq_freq_attr_ro(energy_performance_available_preferences);
>> +define_one_global_rw(status);
>>  
>>  static struct freq_attr *amd_pstate_attr[] = {
>>  	&amd_pstate_max_freq,
>> @@ -794,6 +884,15 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
>>  	NULL,
>>  };
>>  
>> +static struct attribute *pstate_global_attributes[] = {
>> +	&status.attr,
>> +	NULL
>> +};
>> +
>> +static const struct attribute_group amd_pstate_global_attr_group = {
>> +	.attrs = pstate_global_attributes,
>> +};
>> +
>>  static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
>>  {
>>  	int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
>> @@ -1153,6 +1252,25 @@ static int __init amd_pstate_init(void)
>>  	if (ret)
>>  		pr_err("failed to register with return %d\n", ret);
>>  
>> +	amd_pstate_kobj = kobject_create_and_add("amd_pstate", &cpu_subsys.dev_root->kobj);
>> +	if (!amd_pstate_kobj) {
>> +		ret = -EINVAL;
>> +		pr_err("global sysfs registration failed.\n");
>> +		goto kobject_free;
>> +	}
>> +
>> +	ret = sysfs_create_group(amd_pstate_kobj, &amd_pstate_global_attr_group);
>> +	if (ret) {
>> +		pr_err("sysfs attribute export failed with error %d.\n", ret);
>> +		goto global_attr_free;
>> +	}
>> +
>> +	return ret;
>> +
>> +global_attr_free:
>> +	kobject_put(amd_pstate_kobj);
>> +kobject_free:
>> +	cpufreq_unregister_driver(current_pstate_driver);
>>  	return ret;
>>  }
>>  device_initcall(amd_pstate_init);
>> -- 
>> 2.34.1
>>

-- 
Thanks & Regards,
Wyes