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Message-ID: <DM4PR12MB5278B9BD3DB938CF4EC628D69CEF9@DM4PR12MB5278.namprd12.prod.outlook.com>
Date: Sun, 25 Dec 2022 16:41:50 +0000
From: "Yuan, Perry" <Perry.Yuan@....com>
To: "Huang, Ray" <Ray.Huang@....com>
CC: "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
"Limonciello, Mario" <Mario.Limonciello@....com>,
"viresh.kumar@...aro.org" <viresh.kumar@...aro.org>,
"Sharma, Deepak" <Deepak.Sharma@....com>,
"Fontenot, Nathan" <Nathan.Fontenot@....com>,
"Deucher, Alexander" <Alexander.Deucher@....com>,
"Huang, Shimmer" <Shimmer.Huang@....com>,
"Du, Xiaojian" <Xiaojian.Du@....com>,
"Meng, Li (Jassmine)" <Li.Meng@....com>,
"Karny, Wyes" <Wyes.Karny@....com>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v8 09/13] cpufreq: amd-pstate: add driver working mode
switch support
[AMD Official Use Only - General]
> -----Original Message-----
> From: Huang, Ray <Ray.Huang@....com>
> Sent: Friday, December 23, 2022 4:56 PM
> To: Yuan, Perry <Perry.Yuan@....com>
> Cc: rafael.j.wysocki@...el.com; Limonciello, Mario
> <Mario.Limonciello@....com>; viresh.kumar@...aro.org; Sharma, Deepak
> <Deepak.Sharma@....com>; Fontenot, Nathan
> <Nathan.Fontenot@....com>; Deucher, Alexander
> <Alexander.Deucher@....com>; Huang, Shimmer
> <Shimmer.Huang@....com>; Du, Xiaojian <Xiaojian.Du@....com>; Meng,
> Li (Jassmine) <Li.Meng@....com>; Karny, Wyes <Wyes.Karny@....com>;
> linux-pm@...r.kernel.org; linux-kernel@...r.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@....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@....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
> >
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