[v8] Implement AMD Pstate EPP Driver

[PATCH v8 09/13] cpufreq: amd-pstate: add driver working mode switch support

Posted by Perry Yuan 2 years, 9 months ago

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>
---
 drivers/cpufreq/amd-pstate.c | 128 +++++++++++++++++++++++++++++++++++
 1 file changed, 128 insertions(+)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index fc12d35bc7bd..e8996e937e63 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -64,6 +64,7 @@ static struct cpufreq_driver amd_pstate_driver;
 static struct cpufreq_driver amd_pstate_epp_driver;
 static struct amd_cpudata **all_cpu_data;
 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)
 {
@@ -90,6 +91,8 @@ static struct amd_pstate_params global_params;
 static DEFINE_MUTEX(amd_pstate_limits_lock);
 static DEFINE_MUTEX(amd_pstate_driver_lock);
 
+static DEFINE_SPINLOCK(cppc_notify_lock);
+
 static s16 amd_pstate_get_epp(struct amd_cpudata *cpudata, u64 cppc_req_cached)
 {
 	u64 epp;
@@ -644,6 +647,8 @@ 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;
 
@@ -784,12 +789,106 @@ 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 (!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_driver_cleanup(void)
+{
+	unsigned int cpu;
+
+	cpus_read_lock();
+	for_each_online_cpu(cpu) {
+		if (all_cpu_data[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_state == AMD_PSTATE_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;
+			cppc_state = AMD_PSTATE_ACTIVE;
+		}
+
+		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);
+			cppc_state = AMD_PSTATE_PASSIVE;
+			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);
 
 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,
@@ -807,6 +906,15 @@ 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 inline void update_boost_state(void)
 {
 	u64 misc_en;
@@ -1228,6 +1336,26 @@ 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:
+	kfree(cpudata);
+	cpufreq_unregister_driver(default_pstate_driver);
 	return ret;
 }
 device_initcall(amd_pstate_init);
-- 
2.34.1

Re: [PATCH v8 09/13] cpufreq: amd-pstate: add driver working mode switch support

Posted by Huang Rui 2 years, 8 months ago

On Mon, Dec 19, 2022 at 02:40:38PM +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>
> ---
>  drivers/cpufreq/amd-pstate.c | 128 +++++++++++++++++++++++++++++++++++
>  1 file changed, 128 insertions(+)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index fc12d35bc7bd..e8996e937e63 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -64,6 +64,7 @@ static struct cpufreq_driver amd_pstate_driver;
>  static struct cpufreq_driver amd_pstate_epp_driver;
>  static struct amd_cpudata **all_cpu_data;
>  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)
>  {
> @@ -90,6 +91,8 @@ static struct amd_pstate_params global_params;
>  static DEFINE_MUTEX(amd_pstate_limits_lock);
>  static DEFINE_MUTEX(amd_pstate_driver_lock);
>  
> +static DEFINE_SPINLOCK(cppc_notify_lock);
> +
>  static s16 amd_pstate_get_epp(struct amd_cpudata *cpudata, u64 cppc_req_cached)
>  {
>  	u64 epp;
> @@ -644,6 +647,8 @@ 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;

If default_driver is passive driver, it will be programed as
amd_pstate_adjust_perf. If not, the epp driver won't need adjust_perf.

Thanks,
Ray

>  
>  	return 0;
>  
> @@ -784,12 +789,106 @@ 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 (!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_driver_cleanup(void)
> +{
> +	unsigned int cpu;
> +
> +	cpus_read_lock();
> +	for_each_online_cpu(cpu) {
> +		if (all_cpu_data[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_state == AMD_PSTATE_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;
> +			cppc_state = AMD_PSTATE_ACTIVE;
> +		}
> +
> +		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);
> +			cppc_state = AMD_PSTATE_PASSIVE;
> +			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);
>  
>  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,
> @@ -807,6 +906,15 @@ 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 inline void update_boost_state(void)
>  {
>  	u64 misc_en;
> @@ -1228,6 +1336,26 @@ 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:
> +	kfree(cpudata);
> +	cpufreq_unregister_driver(default_pstate_driver);
>  	return ret;
>  }
>  device_initcall(amd_pstate_init);
> -- 
> 2.34.1
>

RE: [PATCH v8 09/13] cpufreq: amd-pstate: add driver working mode switch support

Posted by Yuan, Perry 2 years, 8 months ago

[AMD Official Use Only - General]



> -----Original Message-----
> From: Huang, Ray <Ray.Huang@amd.com>
> Sent: Friday, December 23, 2022 4:56 PM
> To: Yuan, Perry <Perry.Yuan@amd.com>
> Cc: rafael.j.wysocki@intel.com; Limonciello, Mario
> <Mario.Limonciello@amd.com>; 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-kernel@vger.kernel.org
> Subject: Re: [PATCH v8 09/13] cpufreq: amd-pstate: add driver working mode
> switch support
> 
> On Mon, Dec 19, 2022 at 02:40:38PM +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>
> > ---
> >  drivers/cpufreq/amd-pstate.c | 128
> > +++++++++++++++++++++++++++++++++++
> >  1 file changed, 128 insertions(+)
> >
> > diff --git a/drivers/cpufreq/amd-pstate.c
> > b/drivers/cpufreq/amd-pstate.c index fc12d35bc7bd..e8996e937e63
> 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -64,6 +64,7 @@ static struct cpufreq_driver amd_pstate_driver;
> > static struct cpufreq_driver amd_pstate_epp_driver;  static struct
> > amd_cpudata **all_cpu_data;  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)
> > { @@ -90,6 +91,8 @@ static struct amd_pstate_params global_params;
> > static DEFINE_MUTEX(amd_pstate_limits_lock);
> >  static DEFINE_MUTEX(amd_pstate_driver_lock);
> >
> > +static DEFINE_SPINLOCK(cppc_notify_lock);
> > +
> >  static s16 amd_pstate_get_epp(struct amd_cpudata *cpudata, u64
> > cppc_req_cached)  {
> >  	u64 epp;
> > @@ -644,6 +647,8 @@ 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;
> 
> If default_driver is passive driver, it will be programed as
> amd_pstate_adjust_perf. If not, the epp driver won't need adjust_perf.
> 
> Thanks,
> Ray

The adjust_perf() should be set again when switching from epp to cppc driver.
The above amd_pstate_cpu_init ()  is called when amd-pstate driver loading, epp driver will not load it.


> 
> >
> >  	return 0;
> >
> > @@ -784,12 +789,106 @@ 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 (!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_driver_cleanup(void) {
> > +	unsigned int cpu;
> > +
> > +	cpus_read_lock();
> > +	for_each_online_cpu(cpu) {
> > +		if (all_cpu_data[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_state == AMD_PSTATE_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;
> > +			cppc_state = AMD_PSTATE_ACTIVE;
> > +		}
> > +
> > +		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);
> > +			cppc_state = AMD_PSTATE_PASSIVE;
> > +			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);
> >
> >  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,
> > @@ -807,6 +906,15 @@ 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 inline void update_boost_state(void)  {
> >  	u64 misc_en;
> > @@ -1228,6 +1336,26 @@ 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:
> > +	kfree(cpudata);
> > +	cpufreq_unregister_driver(default_pstate_driver);
> >  	return ret;
> >  }
> >  device_initcall(amd_pstate_init);
> > --
> > 2.34.1
> >

Re: [PATCH v8 09/13] cpufreq: amd-pstate: add driver working mode switch support

Posted by Limonciello, Mario 2 years, 9 months ago

On 12/19/2022 00:40, Perry Yuan 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>
> ---
>   drivers/cpufreq/amd-pstate.c | 128 +++++++++++++++++++++++++++++++++++
>   1 file changed, 128 insertions(+)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index fc12d35bc7bd..e8996e937e63 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -64,6 +64,7 @@ static struct cpufreq_driver amd_pstate_driver;
>   static struct cpufreq_driver amd_pstate_epp_driver;
>   static struct amd_cpudata **all_cpu_data;
>   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)
>   {
> @@ -90,6 +91,8 @@ static struct amd_pstate_params global_params;
>   static DEFINE_MUTEX(amd_pstate_limits_lock);
>   static DEFINE_MUTEX(amd_pstate_driver_lock);
>   
> +static DEFINE_SPINLOCK(cppc_notify_lock);
> +
>   static s16 amd_pstate_get_epp(struct amd_cpudata *cpudata, u64 cppc_req_cached)
>   {
>   	u64 epp;
> @@ -644,6 +647,8 @@ 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;
>   
> @@ -784,12 +789,106 @@ 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 (!default_pstate_driver)
> +		return sysfs_emit(buf, "off\n");
> +
> +	return sysfs_emit(buf, "%s\n", default_pstate_driver == &amd_pstate_epp_driver ?
> +					"active" : "passive");

Didn't you introduce const strings for this in an earlier patch from the 
series?

How about using the indices from that rather than hardcoding /another/ 
string.

Also keep in mind guided mode will be coming so
"case ? true_val : false_val"

So perhaps you should just have have some if cases so you don't have to 
switch the whole thing out.

> +}
> +
> +static void amd_pstate_driver_cleanup(void)
> +{
> +	unsigned int cpu;
> +
> +	cpus_read_lock();
> +	for_each_online_cpu(cpu) {
> +		if (all_cpu_data[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)
> +{

Rather than looking at each size for each case, how about you just look 
at the boundaries once?  Something like this:

if (size > 7 || size < 3)
	return -EINVAL;

Then you should be able to run strncmp for each of your cases.

> +	if (size == 3 && !strncmp(buf, "off", size)) {

This seems like another case that would be good to use the const strings 
you already introduced for state machine checking.

> +		if (!default_pstate_driver)
> +			return -EINVAL;
> +
> +		if (cppc_state == AMD_PSTATE_ACTIVE)
> +			return -EBUSY;
> +
> +		cpufreq_unregister_driver(default_pstate_driver);
> +		amd_pstate_driver_cleanup();
> +		return 0;
> +	}
> +
> +	if (size == 6 && !strncmp(buf, "active", size)) {

This seems like another case that would be good to use the const strings 
you already introduced for state machine checking.

> +		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;
> +			cppc_state = AMD_PSTATE_ACTIVE;
> +		}
> +
> +		return cpufreq_register_driver(default_pstate_driver);
> +	}
> +
> +	if (size == 7 && !strncmp(buf, "passive", size)) {

This seems like another case that would be good to use the const strings 
you already introduced for state machine checking.

> +		if (default_pstate_driver) {
> +			if (default_pstate_driver == &amd_pstate_driver)
> +				return 0;
> +			cpufreq_unregister_driver(default_pstate_driver);
> +			cppc_state = AMD_PSTATE_PASSIVE;
> +			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);
>   
>   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,
> @@ -807,6 +906,15 @@ 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 inline void update_boost_state(void)
>   {
>   	u64 misc_en;
> @@ -1228,6 +1336,26 @@ 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:
> +	kfree(cpudata);
> +	cpufreq_unregister_driver(default_pstate_driver);
>   	return ret;
>   }
>   device_initcall(amd_pstate_init);