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Date:   Mon, 12 Dec 2022 18:24:07 +0800
From:   Huang Rui <ray.huang@amd.com>
To:     "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>,
        "Karny, Wyes" <Wyes.Karny@amd.com>,
        "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v7 09/13] cpufreq: amd-pstate: add driver working mode
 status sysfs entry
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References: <20221208111852.386731-1-perry.yuan@amd.com>
 <20221208111852.386731-10-perry.yuan@amd.com>
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On Thu, Dec 08, 2022 at 07:18:48PM +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"
> 
> Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>

I believe you should align with Wyes to send out a unify state or status
API to indicate the state machine of different work mode for AMD P-State
driver including active and guided mode.

Thanks,
Ray

> ---
>  drivers/cpufreq/amd-pstate.c | 101 +++++++++++++++++++++++++++++++++++
>  1 file changed, 101 insertions(+)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 4cd53c010215..c90aee3ee42d 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -64,6 +64,8 @@ static bool cppc_active;
>  static int cppc_load __initdata;
>  
>  static struct cpufreq_driver *default_pstate_driver;
> +static struct cpufreq_driver amd_pstate_epp_driver;
> +static struct cpufreq_driver amd_pstate_driver;
>  static struct amd_cpudata **all_cpu_data;
>  static struct amd_pstate_params global_params;
>  
> @@ -72,6 +74,7 @@ static DEFINE_MUTEX(amd_pstate_driver_lock);
>  struct kobject *amd_pstate_kobj;
>  
>  static bool cppc_boost __read_mostly;
> +static DEFINE_SPINLOCK(cppc_notify_lock);
>  
>  static s16 amd_pstate_get_epp(struct amd_cpudata *cpudata, u64 cppc_req_cached)
>  {
> @@ -629,6 +632,8 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
>  	policy->driver_data = cpudata;
>  
>  	amd_pstate_boost_init(cpudata);
> +	if (!default_pstate_driver->adjust_perf)
> +		default_pstate_driver->adjust_perf = amd_pstate_adjust_perf;
>  
>  	return 0;
>  
> @@ -802,6 +807,100 @@ static ssize_t store_cppc_dynamic_boost(struct kobject *a,
>  	return count;
>  }
>  
> +static ssize_t amd_pstate_show_status(char *buf)
> +{
> +	if (!default_pstate_driver)
> +		return sysfs_emit(buf, "off\n");
> +
> +	return sysfs_emit(buf, "%s\n", default_pstate_driver == &amd_pstate_epp_driver ?
> +					"active" : "passive");
> +}
> +
> +static void amd_pstate_clear_update_util_hook(unsigned int cpu);
> +static void amd_pstate_driver_cleanup(void)
> +{
> +	unsigned int cpu;
> +
> +	cpus_read_lock();
> +	for_each_online_cpu(cpu) {
> +		if (all_cpu_data[cpu]) {
> +			if (default_pstate_driver == &amd_pstate_epp_driver)
> +				amd_pstate_clear_update_util_hook(cpu);
> +
> +			spin_lock(&cppc_notify_lock);
> +			kfree(all_cpu_data[cpu]);
> +			WRITE_ONCE(all_cpu_data[cpu], NULL);
> +			spin_unlock(&cppc_notify_lock);
> +		}
> +	}
> +	cpus_read_unlock();
> +
> +	default_pstate_driver = NULL;
> +}
> +
> +static int amd_pstate_update_status(const char *buf, size_t size)
> +{
> +	if (size == 3 && !strncmp(buf, "off", size)) {
> +		if (!default_pstate_driver)
> +			return -EINVAL;
> +
> +		if (cppc_active)
> +			return -EBUSY;
> +
> +		cpufreq_unregister_driver(default_pstate_driver);
> +		amd_pstate_driver_cleanup();
> +		return 0;
> +	}
> +
> +	if (size == 6 && !strncmp(buf, "active", size)) {
> +		if (default_pstate_driver) {
> +			if (default_pstate_driver == &amd_pstate_epp_driver)
> +				return 0;
> +			cpufreq_unregister_driver(default_pstate_driver);
> +			default_pstate_driver = &amd_pstate_epp_driver;
> +		}
> +
> +		return cpufreq_register_driver(default_pstate_driver);
> +	}
> +
> +	if (size == 7 && !strncmp(buf, "passive", size)) {
> +		if (default_pstate_driver) {
> +			if (default_pstate_driver == &amd_pstate_driver)
> +				return 0;
> +			cpufreq_unregister_driver(default_pstate_driver);
> +		}
> +		default_pstate_driver = &amd_pstate_driver;
> +		return cpufreq_register_driver(default_pstate_driver);
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +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);
>  
> @@ -809,6 +908,7 @@ 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(cppc_dynamic_boost);
> +define_one_global_rw(status);
>  
>  static struct freq_attr *amd_pstate_attr[] = {
>  	&amd_pstate_max_freq,
> @@ -828,6 +928,7 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
>  
>  static struct attribute *pstate_global_attributes[] = {
>  	&cppc_dynamic_boost.attr,
> +	&status.attr,
>  	NULL
>  };
>  
> -- 
> 2.34.1
>