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From:   "Yuan, Perry" <Perry.Yuan@amd.com>
To:     "Huang, Ray" <Ray.Huang@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 v8 09/13] cpufreq: amd-pstate: add driver working mode
 switch support
Thread-Topic: [PATCH v8 09/13] cpufreq: amd-pstate: add driver working mode
 switch support
Thread-Index: AQHZE3U4TKgox8MrB0eBMbwmECJHIq57Me8AgAOlZCA=
Date:   Sun, 25 Dec 2022 16:41:50 +0000
Message-ID: <DM4PR12MB5278B9BD3DB938CF4EC628D69CEF9@DM4PR12MB5278.namprd12.prod.outlook.com>
References: <20221219064042.661122-1-perry.yuan@amd.com>
 <20221219064042.661122-10-perry.yuan@amd.com> <Y6VtNOgfohaewEtW@amd.com>
In-Reply-To: <Y6VtNOgfohaewEtW@amd.com>
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[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 mod=
e
> switch support
>=20
> 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 =3D
> > 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 =3D cpudata;
> >
> >  	amd_pstate_boost_init(cpudata);
> > +	if (!default_pstate_driver->adjust_perf)
> > +		default_pstate_driver->adjust_perf =3D
> amd_pstate_adjust_perf;
>=20
> 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.
>=20
> Thanks,
> Ray

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


>=20
> >
> >  	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 =3D=3D
> &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 =3D NULL;
> > +}
> > +
> > +static int amd_pstate_update_status(const char *buf, size_t size) {
> > +	if (size =3D=3D 3 && !strncmp(buf, "off", size)) {
> > +		if (!default_pstate_driver)
> > +			return -EINVAL;
> > +
> > +		if (cppc_state =3D=3D AMD_PSTATE_ACTIVE)
> > +			return -EBUSY;
> > +
> > +		cpufreq_unregister_driver(default_pstate_driver);
> > +		amd_pstate_driver_cleanup();
> > +		return 0;
> > +	}
> > +
> > +	if (size =3D=3D 6 && !strncmp(buf, "active", size)) {
> > +		if (default_pstate_driver) {
> > +			if (default_pstate_driver =3D=3D
> &amd_pstate_epp_driver)
> > +				return 0;
> > +			cpufreq_unregister_driver(default_pstate_driver);
> > +			default_pstate_driver =3D &amd_pstate_epp_driver;
> > +			cppc_state =3D AMD_PSTATE_ACTIVE;
> > +		}
> > +
> > +		return cpufreq_register_driver(default_pstate_driver);
> > +	}
> > +
> > +	if (size =3D=3D 7 && !strncmp(buf, "passive", size)) {
> > +		if (default_pstate_driver) {
> > +			if (default_pstate_driver =3D=3D &amd_pstate_driver)
> > +				return 0;
> > +			cpufreq_unregister_driver(default_pstate_driver);
> > +			cppc_state =3D AMD_PSTATE_PASSIVE;
> > +			default_pstate_driver =3D &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 =3D 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 =3D memchr(buf, '\n', count);
> > +	int ret;
> > +
> > +	mutex_lock(&amd_pstate_driver_lock);
> > +	ret =3D 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[] =3D {
> >  	&amd_pstate_max_freq,
> > @@ -807,6 +906,15 @@ static struct freq_attr *amd_pstate_epp_attr[] =3D=
 {
> >  	NULL,
> >  };
> >
> > +static struct attribute *pstate_global_attributes[] =3D {
> > +	&status.attr,
> > +	NULL
> > +};
> > +
> > +static const struct attribute_group amd_pstate_global_attr_group =3D {
> > +	.attrs =3D 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 =3D kobject_create_and_add("amd-pstate",
> &cpu_subsys.dev_root->kobj);
> > +	if (!amd_pstate_kobj) {
> > +		ret =3D -EINVAL;
> > +		pr_err("global sysfs registration failed.\n");
> > +		goto kobject_free;
> > +	}
> > +
> > +	ret =3D 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
> >