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Date: Mon, 12 Dec 2022 18:24:07 +0800
From: Huang Rui <ray.huang@....com>
To: "Yuan, Perry" <Perry.Yuan@....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 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@....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>
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
>
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