RE: [PATCH v7 09/13] cpufreq: amd-pstate: add driver working mode status sysfs entry

[Yuan, Perry]

[AMD Official Use Only - General]



> -----Original Message-----
> From: Huang, Ray <Ray.Huang@xxxxxxx>
> Sent: Monday, December 12, 2022 6:24 PM
> To: Yuan, Perry <Perry.Yuan@xxxxxxx>
> Cc: rafael.j.wysocki@xxxxxxxxx; Limonciello, Mario
> <Mario.Limonciello@xxxxxxx>; viresh.kumar@xxxxxxxxxx; Sharma, Deepak
> <Deepak.Sharma@xxxxxxx>; Fontenot, Nathan
> <Nathan.Fontenot@xxxxxxx>; Deucher, Alexander
> <Alexander.Deucher@xxxxxxx>; Huang, Shimmer
> <Shimmer.Huang@xxxxxxx>; Du, Xiaojian <Xiaojian.Du@xxxxxxx>; Meng,
> Li (Jassmine) <Li.Meng@xxxxxxx>; Karny, Wyes <Wyes.Karny@xxxxxxx>;
> linux-pm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v7 09/13] cpufreq: amd-pstate: add driver working
> mode status sysfs entry
> 
> On Thu, Dec 08, 2022 at 07:18:48PM +0800, Yuan, Perry wrote:
> > From: Perry Yuan <Perry.Yuan@xxxxxxx>
> >
> > 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@xxxxxxx>
> 
> 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
> 

Aligned with Wyse and I add one new working mode switch support patch in V8 adding epp,guide,passive mode in it. 

> > ---
> >  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
> >