[PATCH V4 0/2] firmware: arm_scmi: Register and handle limits change notification

[PATCH V4 0/2] firmware: arm_scmi: Register and handle limits change notification

[Sibi Sankar]

This series registers for scmi limits change notifications to determine
the throttled frequency and apply HW pressure.

V4:
* Use EXPORT_SYMBOL_GPL instead. [Trilok]
* Use a interim variable to show the khz calc. [Lukasz]
* Use driver_data to pass on the handle and scmi_dev instead of using
  global variables. Dropped Lukasz's Rb due to adding these minor
  changes.

V3:
* Sanitize range_max received from the notifier. [Pierre]
* Drop patches 1/2 from v2. [Cristian]
* Update commit message in patch 2.

V2:
* Rename opp_xlate -> freq_xlate [Viresh]
* Export cpufreq_update_pressure and use it directly [Lukasz]

Depends on:
HW pressure v6: https://patchwork.kernel.org/project/linux-arm-msm/cover/20240326091616.3696851-1-vincent.guittot@linaro.org/

Sibi Sankar (2):
  cpufreq: Export cpufreq_update_pressure
  cpufreq: scmi: Register for limit change notifications

 drivers/cpufreq/cpufreq.c      |  3 ++-
 drivers/cpufreq/scmi-cpufreq.c | 44 ++++++++++++++++++++++++++++++++++
 include/linux/cpufreq.h        |  2 ++
 3 files changed, 48 insertions(+), 1 deletion(-)

-- 
2.34.1

[PATCH V4 1/2] cpufreq: Export cpufreq_update_pressure

[Sibi Sankar]

The SCMI cpufreq driver doesn't require any additional signal
smoothing provided by arch_update_hw_pressure interface, export
cpufreq_update_pressure so that it can be called upon directly
instead.

Suggested-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
---

v4:
* Use EXPORT_SYMBOL_GPL instead. [Trilok]

 drivers/cpufreq/cpufreq.c | 3 ++-
 include/linux/cpufreq.h   | 2 ++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 1de8bd105934..656320554bb7 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2590,7 +2590,7 @@ DEFINE_PER_CPU(unsigned long, cpufreq_pressure);
  *
  * Update the value of cpufreq pressure for all @cpus in the policy.
  */
-static void cpufreq_update_pressure(struct cpufreq_policy *policy)
+void cpufreq_update_pressure(struct cpufreq_policy *policy)
 {
 	unsigned long max_capacity, capped_freq, pressure;
 	u32 max_freq;
@@ -2615,6 +2615,7 @@ static void cpufreq_update_pressure(struct cpufreq_policy *policy)
 	for_each_cpu(cpu, policy->related_cpus)
 		WRITE_ONCE(per_cpu(cpufreq_pressure, cpu), pressure);
 }
+EXPORT_SYMBOL_GPL(cpufreq_update_pressure);
 
 /**
  * cpufreq_set_policy - Modify cpufreq policy parameters.
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 20f7e98ee8af..7410a1bade23 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -241,6 +241,7 @@ struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy);
 void cpufreq_enable_fast_switch(struct cpufreq_policy *policy);
 void cpufreq_disable_fast_switch(struct cpufreq_policy *policy);
 bool has_target_index(void);
+void cpufreq_update_pressure(struct cpufreq_policy *policy);
 
 DECLARE_PER_CPU(unsigned long, cpufreq_pressure);
 static inline unsigned long cpufreq_get_pressure(int cpu)
@@ -270,6 +271,7 @@ static inline bool cpufreq_supports_freq_invariance(void)
 }
 static inline void disable_cpufreq(void) { }
 static inline void cpufreq_update_limits(unsigned int cpu) { }
+static inline void cpufreq_update_pressure(struct cpufreq_policy *policy) { }
 static inline unsigned long cpufreq_get_pressure(int cpu)
 {
 	return 0;
-- 
2.34.1

[PATCH V4 2/2] cpufreq: scmi: Register for limit change notifications

[Sibi Sankar]

Register for limit change notifications if supported and use the throttled
frequency from the notification to apply HW pressure.

Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
---

v4:
* Use a interim variable to show the khz calc. [Lukasz]
* Use driver_data to pass on the handle and scmi_dev instead of using
  global variables. Dropped Lukasz's Rb due to adding these minor
  changes.

 drivers/cpufreq/scmi-cpufreq.c | 44 ++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
index 3b4f6bfb2f4c..d946b7a08258 100644
--- a/drivers/cpufreq/scmi-cpufreq.c
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -21,11 +21,18 @@
 #include <linux/types.h>
 #include <linux/units.h>
 
+struct scmi_cpufreq_driver_data {
+	struct scmi_device *sdev;
+	const struct scmi_handle *handle;
+};
+
 struct scmi_data {
 	int domain_id;
 	int nr_opp;
 	struct device *cpu_dev;
+	struct cpufreq_policy *policy;
 	cpumask_var_t opp_shared_cpus;
+	struct notifier_block limit_notify_nb;
 };
 
 static struct scmi_protocol_handle *ph;
@@ -174,6 +181,22 @@ static struct freq_attr *scmi_cpufreq_hw_attr[] = {
 	NULL,
 };
 
+static int scmi_limit_notify_cb(struct notifier_block *nb, unsigned long event, void *data)
+{
+	struct scmi_data *priv = container_of(nb, struct scmi_data, limit_notify_nb);
+	struct scmi_perf_limits_report *limit_notify = data;
+	struct cpufreq_policy *policy = priv->policy;
+	unsigned int limit_freq_khz;
+
+	limit_freq_khz = limit_notify->range_max_freq / HZ_PER_KHZ;
+
+	policy->max = clamp(limit_freq_khz, policy->cpuinfo.min_freq, policy->cpuinfo.max_freq);
+
+	cpufreq_update_pressure(policy);
+
+	return NOTIFY_OK;
+}
+
 static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 {
 	int ret, nr_opp, domain;
@@ -181,6 +204,7 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 	struct device *cpu_dev;
 	struct scmi_data *priv;
 	struct cpufreq_frequency_table *freq_table;
+	struct scmi_cpufreq_driver_data *data = cpufreq_get_driver_data();
 
 	cpu_dev = get_cpu_device(policy->cpu);
 	if (!cpu_dev) {
@@ -294,6 +318,17 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 		}
 	}
 
+	priv->limit_notify_nb.notifier_call = scmi_limit_notify_cb;
+	ret = data->handle->notify_ops->devm_event_notifier_register(data->sdev, SCMI_PROTOCOL_PERF,
+							SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
+							&domain,
+							&priv->limit_notify_nb);
+	if (ret)
+		dev_warn(cpu_dev,
+			 "failed to register for limits change notifier for domain %d\n", domain);
+
+	priv->policy = policy;
+
 	return 0;
 
 out_free_opp:
@@ -366,12 +401,21 @@ static int scmi_cpufreq_probe(struct scmi_device *sdev)
 	int ret;
 	struct device *dev = &sdev->dev;
 	const struct scmi_handle *handle;
+	struct scmi_cpufreq_driver_data *data;
 
 	handle = sdev->handle;
 
 	if (!handle)
 		return -ENODEV;
 
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->sdev = sdev;
+	data->handle = handle;
+	scmi_cpufreq_driver.driver_data = data;
+
 	perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
 	if (IS_ERR(perf_ops))
 		return PTR_ERR(perf_ops);
-- 
2.34.1

Re: [PATCH V4 2/2] cpufreq: scmi: Register for limit change notifications

[Lukasz Luba]

On 3/28/24 07:41, Sibi Sankar wrote:
> Register for limit change notifications if supported and use the throttled
> frequency from the notification to apply HW pressure.
> 
> Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
> ---
> 
> v4:
> * Use a interim variable to show the khz calc. [Lukasz]
> * Use driver_data to pass on the handle and scmi_dev instead of using
>    global variables. Dropped Lukasz's Rb due to adding these minor
>    changes.
> 
>   drivers/cpufreq/scmi-cpufreq.c | 44 ++++++++++++++++++++++++++++++++++
>   1 file changed, 44 insertions(+)
> 
> diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
> index 3b4f6bfb2f4c..d946b7a08258 100644
> --- a/drivers/cpufreq/scmi-cpufreq.c
> +++ b/drivers/cpufreq/scmi-cpufreq.c
> @@ -21,11 +21,18 @@
>   #include <linux/types.h>
>   #include <linux/units.h>
>   
> +struct scmi_cpufreq_driver_data {
> +	struct scmi_device *sdev;
> +	const struct scmi_handle *handle;
> +};
> +
>   struct scmi_data {
>   	int domain_id;
>   	int nr_opp;
>   	struct device *cpu_dev;
> +	struct cpufreq_policy *policy;
>   	cpumask_var_t opp_shared_cpus;
> +	struct notifier_block limit_notify_nb;
>   };
>   
>   static struct scmi_protocol_handle *ph;
> @@ -174,6 +181,22 @@ static struct freq_attr *scmi_cpufreq_hw_attr[] = {
>   	NULL,
>   };
>   
> +static int scmi_limit_notify_cb(struct notifier_block *nb, unsigned long event, void *data)
> +{
> +	struct scmi_data *priv = container_of(nb, struct scmi_data, limit_notify_nb);
> +	struct scmi_perf_limits_report *limit_notify = data;
> +	struct cpufreq_policy *policy = priv->policy;
> +	unsigned int limit_freq_khz;
> +
> +	limit_freq_khz = limit_notify->range_max_freq / HZ_PER_KHZ;
> +
> +	policy->max = clamp(limit_freq_khz, policy->cpuinfo.min_freq, policy->cpuinfo.max_freq);
> +
> +	cpufreq_update_pressure(policy);
> +
> +	return NOTIFY_OK;
> +}
> +
>   static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>   {
>   	int ret, nr_opp, domain;
> @@ -181,6 +204,7 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>   	struct device *cpu_dev;
>   	struct scmi_data *priv;
>   	struct cpufreq_frequency_table *freq_table;
> +	struct scmi_cpufreq_driver_data *data = cpufreq_get_driver_data();
>   
>   	cpu_dev = get_cpu_device(policy->cpu);
>   	if (!cpu_dev) {
> @@ -294,6 +318,17 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>   		}
>   	}
>   
> +	priv->limit_notify_nb.notifier_call = scmi_limit_notify_cb;
> +	ret = data->handle->notify_ops->devm_event_notifier_register(data->sdev, SCMI_PROTOCOL_PERF,
> +							SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
> +							&domain,
> +							&priv->limit_notify_nb);
> +	if (ret)
> +		dev_warn(cpu_dev,
> +			 "failed to register for limits change notifier for domain %d\n", domain);
> +
> +	priv->policy = policy;
> +
>   	return 0;
>   
>   out_free_opp:
> @@ -366,12 +401,21 @@ static int scmi_cpufreq_probe(struct scmi_device *sdev)
>   	int ret;
>   	struct device *dev = &sdev->dev;
>   	const struct scmi_handle *handle;
> +	struct scmi_cpufreq_driver_data *data;
>   
>   	handle = sdev->handle;
>   
>   	if (!handle)
>   		return -ENODEV;
>   
> +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->sdev = sdev;
> +	data->handle = handle;
> +	scmi_cpufreq_driver.driver_data = data;
> +
>   	perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
>   	if (IS_ERR(perf_ops))
>   		return PTR_ERR(perf_ops);

LGTM,

Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>

Re: [PATCH V4 2/2] cpufreq: scmi: Register for limit change notifications

[Cristian Marussi]

On Thu, Mar 28, 2024 at 01:11:31PM +0530, Sibi Sankar wrote:
> Register for limit change notifications if supported and use the throttled
> frequency from the notification to apply HW pressure.
> 

Hi Sibi,

a bit late on this, sorry.

Just a couple of nitpicks down below.

> Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
> ---
> 
> v4:
> * Use a interim variable to show the khz calc. [Lukasz]
> * Use driver_data to pass on the handle and scmi_dev instead of using
>   global variables. Dropped Lukasz's Rb due to adding these minor
>   changes.
> 
>  drivers/cpufreq/scmi-cpufreq.c | 44 ++++++++++++++++++++++++++++++++++
>  1 file changed, 44 insertions(+)
> 
> diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
> index 3b4f6bfb2f4c..d946b7a08258 100644
> --- a/drivers/cpufreq/scmi-cpufreq.c
> +++ b/drivers/cpufreq/scmi-cpufreq.c
> @@ -21,11 +21,18 @@
>  #include <linux/types.h>
>  #include <linux/units.h>
>  
> +struct scmi_cpufreq_driver_data {
> +	struct scmi_device *sdev;
> +	const struct scmi_handle *handle;
> +};
> +
>  struct scmi_data {
>  	int domain_id;
>  	int nr_opp;
>  	struct device *cpu_dev;
> +	struct cpufreq_policy *policy;
>  	cpumask_var_t opp_shared_cpus;
> +	struct notifier_block limit_notify_nb;
>  };
>  
>  static struct scmi_protocol_handle *ph;
> @@ -174,6 +181,22 @@ static struct freq_attr *scmi_cpufreq_hw_attr[] = {
>  	NULL,
>  };
>  
> +static int scmi_limit_notify_cb(struct notifier_block *nb, unsigned long event, void *data)
> +{
> +	struct scmi_data *priv = container_of(nb, struct scmi_data, limit_notify_nb);
> +	struct scmi_perf_limits_report *limit_notify = data;
> +	struct cpufreq_policy *policy = priv->policy;
> +	unsigned int limit_freq_khz;
> +
> +	limit_freq_khz = limit_notify->range_max_freq / HZ_PER_KHZ;
> +
> +	policy->max = clamp(limit_freq_khz, policy->cpuinfo.min_freq, policy->cpuinfo.max_freq);
> +
> +	cpufreq_update_pressure(policy);
> +
> +	return NOTIFY_OK;
> +}
> +
>  static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>  {
>  	int ret, nr_opp, domain;
> @@ -181,6 +204,7 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>  	struct device *cpu_dev;
>  	struct scmi_data *priv;
>  	struct cpufreq_frequency_table *freq_table;
> +	struct scmi_cpufreq_driver_data *data = cpufreq_get_driver_data();
>  
>  	cpu_dev = get_cpu_device(policy->cpu);
>  	if (!cpu_dev) {
> @@ -294,6 +318,17 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>  		}
>  	}
>  
> +	priv->limit_notify_nb.notifier_call = scmi_limit_notify_cb;
> +	ret = data->handle->notify_ops->devm_event_notifier_register(data->sdev, SCMI_PROTOCOL_PERF,
> +							SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
> +							&domain,
> +							&priv->limit_notify_nb);
> +	if (ret)
> +		dev_warn(cpu_dev,

or &data->sdev->dev which refers to this driver ? which is more informational ? no strong opinion just a question...

> +			 "failed to register for limits change notifier for domain %d\n", domain);
> +
> +	priv->policy = policy;
> +
>  	return 0;
>  
>  out_free_opp:
> @@ -366,12 +401,21 @@ static int scmi_cpufreq_probe(struct scmi_device *sdev)
>  	int ret;
>  	struct device *dev = &sdev->dev;
>  	const struct scmi_handle *handle;
> +	struct scmi_cpufreq_driver_data *data;
>  
>  	handle = sdev->handle;

	^^^ ....
>  
>  	if (!handle)
>  		return -ENODEV;
>  
> +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->sdev = sdev;
> +	data->handle = handle;

	^^^ ... you dont need to pass around handle AND sdev really
                since you can access the handle from sdev.

> +	scmi_cpufreq_driver.driver_data = data;

This is slightly better, but, as said, does not solve the multi-instance issue...
...the scmi cpufreq driver remains a driver that works only if instantiated (probed)
once, given how the CPUFreq core handles cpufreq_driver registration itself...

...just a note about something to work on in the future...NOT a concern for this series.

In general,

LGTM.

Thanks,
Cristian

Re: [PATCH V4 2/2] cpufreq: scmi: Register for limit change notifications

[Cristian Marussi]

On Wed, May 01, 2024 at 09:21:30AM +0100, Cristian Marussi wrote:
> On Thu, Mar 28, 2024 at 01:11:31PM +0530, Sibi Sankar wrote:
> > Register for limit change notifications if supported and use the throttled
> > frequency from the notification to apply HW pressure.
> > 
> 
> Hi Sibi,
> 
> a bit late on this, sorry.
> 

...forgot the tag :P

> Just a couple of nitpicks down below.

[snip]

> In general,
> 
> LGTM.
> 

Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>

Thanks,
Cristian

Re: [PATCH V4 2/2] cpufreq: scmi: Register for limit change notifications

[Sibi Sankar]

On 5/1/24 13:51, Cristian Marussi wrote:
> On Thu, Mar 28, 2024 at 01:11:31PM +0530, Sibi Sankar wrote:
>> Register for limit change notifications if supported and use the throttled
>> frequency from the notification to apply HW pressure.
>>
> 
> Hi Sibi,
> 
> a bit late on this, sorry.
> 
> Just a couple of nitpicks down below.
> 
>> Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
>> ---
>>
>> v4:
>> * Use a interim variable to show the khz calc. [Lukasz]
>> * Use driver_data to pass on the handle and scmi_dev instead of using
>>    global variables. Dropped Lukasz's Rb due to adding these minor
>>    changes.
>>
>>   drivers/cpufreq/scmi-cpufreq.c | 44 ++++++++++++++++++++++++++++++++++
>>   1 file changed, 44 insertions(+)
>>
>> diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
>> index 3b4f6bfb2f4c..d946b7a08258 100644
>> --- a/drivers/cpufreq/scmi-cpufreq.c
>> +++ b/drivers/cpufreq/scmi-cpufreq.c
>> @@ -21,11 +21,18 @@
>>   #include <linux/types.h>
>>   #include <linux/units.h>
>>   
>> +struct scmi_cpufreq_driver_data {
>> +	struct scmi_device *sdev;
>> +	const struct scmi_handle *handle;
>> +};
>> +
>>   struct scmi_data {
>>   	int domain_id;
>>   	int nr_opp;
>>   	struct device *cpu_dev;
>> +	struct cpufreq_policy *policy;
>>   	cpumask_var_t opp_shared_cpus;
>> +	struct notifier_block limit_notify_nb;
>>   };
>>   
>>   static struct scmi_protocol_handle *ph;
>> @@ -174,6 +181,22 @@ static struct freq_attr *scmi_cpufreq_hw_attr[] = {
>>   	NULL,
>>   };
>>   
>> +static int scmi_limit_notify_cb(struct notifier_block *nb, unsigned long event, void *data)
>> +{
>> +	struct scmi_data *priv = container_of(nb, struct scmi_data, limit_notify_nb);
>> +	struct scmi_perf_limits_report *limit_notify = data;
>> +	struct cpufreq_policy *policy = priv->policy;
>> +	unsigned int limit_freq_khz;
>> +
>> +	limit_freq_khz = limit_notify->range_max_freq / HZ_PER_KHZ;
>> +
>> +	policy->max = clamp(limit_freq_khz, policy->cpuinfo.min_freq, policy->cpuinfo.max_freq);
>> +
>> +	cpufreq_update_pressure(policy);
>> +
>> +	return NOTIFY_OK;
>> +}
>> +
>>   static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>>   {
>>   	int ret, nr_opp, domain;
>> @@ -181,6 +204,7 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>>   	struct device *cpu_dev;
>>   	struct scmi_data *priv;
>>   	struct cpufreq_frequency_table *freq_table;
>> +	struct scmi_cpufreq_driver_data *data = cpufreq_get_driver_data();
>>   
>>   	cpu_dev = get_cpu_device(policy->cpu);
>>   	if (!cpu_dev) {
>> @@ -294,6 +318,17 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>>   		}
>>   	}
>>   
>> +	priv->limit_notify_nb.notifier_call = scmi_limit_notify_cb;
>> +	ret = data->handle->notify_ops->devm_event_notifier_register(data->sdev, SCMI_PROTOCOL_PERF,
>> +							SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
>> +							&domain,
>> +							&priv->limit_notify_nb);
>> +	if (ret)
>> +		dev_warn(cpu_dev,
> 
> or &data->sdev->dev which refers to this driver ? which is more informational ? no strong opinion just a question...

Pointing to the driver is better given that we already pass on domain
info.

> 
>> +			 "failed to register for limits change notifier for domain %d\n", domain);
>> +
>> +	priv->policy = policy;
>> +
>>   	return 0;
>>   
>>   out_free_opp:
>> @@ -366,12 +401,21 @@ static int scmi_cpufreq_probe(struct scmi_device *sdev)
>>   	int ret;
>>   	struct device *dev = &sdev->dev;
>>   	const struct scmi_handle *handle;
>> +	struct scmi_cpufreq_driver_data *data;
>>   
>>   	handle = sdev->handle;
> 
> 	^^^ ....
>>   
>>   	if (!handle)
>>   		return -ENODEV;
>>   
>> +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
>> +	if (!data)
>> +		return -ENOMEM;
>> +
>> +	data->sdev = sdev;
>> +	data->handle = handle;
> 
> 	^^^ ... you dont need to pass around handle AND sdev really
>                  since you can access the handle from sdev.
> 
>> +	scmi_cpufreq_driver.driver_data = data;

Ack setting sdev as driver data would suffice. Will fix it in the next
re-spin.

-Sibi

> 
> This is slightly better, but, as said, does not solve the multi-instance issue...
> ...the scmi cpufreq driver remains a driver that works only if instantiated (probed)
> once, given how the CPUFreq core handles cpufreq_driver registration itself...
> 
> ...just a note about something to work on in the future...NOT a concern for this series.
> 
> In general,
> 
> LGTM.
> 
> Thanks,
> Cristian
> 

Re: [PATCH V4 2/2] cpufreq: scmi: Register for limit change notifications

[Vincent Guittot]

Hi Sibi,

On Thu, 28 Mar 2024 at 08:42, Sibi Sankar <quic_sibis@quicinc.com> wrote:
>
> Register for limit change notifications if supported and use the throttled
> frequency from the notification to apply HW pressure.
>
> Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
> ---
>
> v4:
> * Use a interim variable to show the khz calc. [Lukasz]
> * Use driver_data to pass on the handle and scmi_dev instead of using
>   global variables. Dropped Lukasz's Rb due to adding these minor
>   changes.
>
>  drivers/cpufreq/scmi-cpufreq.c | 44 ++++++++++++++++++++++++++++++++++
>  1 file changed, 44 insertions(+)
>
> diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
> index 3b4f6bfb2f4c..d946b7a08258 100644
> --- a/drivers/cpufreq/scmi-cpufreq.c
> +++ b/drivers/cpufreq/scmi-cpufreq.c
> @@ -21,11 +21,18 @@
>  #include <linux/types.h>
>  #include <linux/units.h>
>
> +struct scmi_cpufreq_driver_data {
> +       struct scmi_device *sdev;
> +       const struct scmi_handle *handle;
> +};
> +
>  struct scmi_data {
>         int domain_id;
>         int nr_opp;
>         struct device *cpu_dev;
> +       struct cpufreq_policy *policy;
>         cpumask_var_t opp_shared_cpus;
> +       struct notifier_block limit_notify_nb;
>  };
>
>  static struct scmi_protocol_handle *ph;
> @@ -174,6 +181,22 @@ static struct freq_attr *scmi_cpufreq_hw_attr[] = {
>         NULL,
>  };
>
> +static int scmi_limit_notify_cb(struct notifier_block *nb, unsigned long event, void *data)
> +{
> +       struct scmi_data *priv = container_of(nb, struct scmi_data, limit_notify_nb);
> +       struct scmi_perf_limits_report *limit_notify = data;
> +       struct cpufreq_policy *policy = priv->policy;
> +       unsigned int limit_freq_khz;
> +
> +       limit_freq_khz = limit_notify->range_max_freq / HZ_PER_KHZ;
> +
> +       policy->max = clamp(limit_freq_khz, policy->cpuinfo.min_freq, policy->cpuinfo.max_freq);
> +
> +       cpufreq_update_pressure(policy);

I noticed your patch while looking for other things in the archive but
I don't think this is the right way to do it.

cpufreq_update_pressure() aims to set to the scheduler the aggregation
of all cappings set to cpufreq through the pm_qos and
freq_qos_add_request(). Calling this function directly in scmi
notification callback will overwrite the pm_qos aggregation. And at
the opposite, any update of a pm_qos constraint will overwrite scmi
notification. Instead you should better set a pm_qos constraint like
others

> +
> +       return NOTIFY_OK;
> +}
> +
>  static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>  {
>         int ret, nr_opp, domain;
> @@ -181,6 +204,7 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>         struct device *cpu_dev;
>         struct scmi_data *priv;
>         struct cpufreq_frequency_table *freq_table;
> +       struct scmi_cpufreq_driver_data *data = cpufreq_get_driver_data();
>
>         cpu_dev = get_cpu_device(policy->cpu);
>         if (!cpu_dev) {
> @@ -294,6 +318,17 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>                 }
>         }
>
> +       priv->limit_notify_nb.notifier_call = scmi_limit_notify_cb;
> +       ret = data->handle->notify_ops->devm_event_notifier_register(data->sdev, SCMI_PROTOCOL_PERF,
> +                                                       SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
> +                                                       &domain,
> +                                                       &priv->limit_notify_nb);
> +       if (ret)
> +               dev_warn(cpu_dev,
> +                        "failed to register for limits change notifier for domain %d\n", domain);
> +
> +       priv->policy = policy;
> +
>         return 0;
>
>  out_free_opp:
> @@ -366,12 +401,21 @@ static int scmi_cpufreq_probe(struct scmi_device *sdev)
>         int ret;
>         struct device *dev = &sdev->dev;
>         const struct scmi_handle *handle;
> +       struct scmi_cpufreq_driver_data *data;
>
>         handle = sdev->handle;
>
>         if (!handle)
>                 return -ENODEV;
>
> +       data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> +       if (!data)
> +               return -ENOMEM;
> +
> +       data->sdev = sdev;
> +       data->handle = handle;
> +       scmi_cpufreq_driver.driver_data = data;
> +
>         perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
>         if (IS_ERR(perf_ops))
>                 return PTR_ERR(perf_ops);
> --
> 2.34.1
>
>

Re: [PATCH V4 2/2] cpufreq: scmi: Register for limit change notifications

[Sibi Sankar]

On 5/28/24 14:38, Vincent Guittot wrote:
> Hi Sibi,
> 

Hey Vincent,
Thanks for taking time to review the series :)

> On Thu, 28 Mar 2024 at 08:42, Sibi Sankar <quic_sibis@quicinc.com> wrote:
>>
>> Register for limit change notifications if supported and use the throttled
>> frequency from the notification to apply HW pressure.
>>
>> Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
>> ---
>>
>> v4:
>> * Use a interim variable to show the khz calc. [Lukasz]
>> * Use driver_data to pass on the handle and scmi_dev instead of using
>>    global variables. Dropped Lukasz's Rb due to adding these minor
>>    changes.
>>
>>   drivers/cpufreq/scmi-cpufreq.c | 44 ++++++++++++++++++++++++++++++++++
>>   1 file changed, 44 insertions(+)
>>
>> diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
>> index 3b4f6bfb2f4c..d946b7a08258 100644
>> --- a/drivers/cpufreq/scmi-cpufreq.c
>> +++ b/drivers/cpufreq/scmi-cpufreq.c
>> @@ -21,11 +21,18 @@
>>   #include <linux/types.h>
>>   #include <linux/units.h>
>>
>> +struct scmi_cpufreq_driver_data {
>> +       struct scmi_device *sdev;
>> +       const struct scmi_handle *handle;
>> +};
>> +
>>   struct scmi_data {
>>          int domain_id;
>>          int nr_opp;
>>          struct device *cpu_dev;
>> +       struct cpufreq_policy *policy;
>>          cpumask_var_t opp_shared_cpus;
>> +       struct notifier_block limit_notify_nb;
>>   };
>>
>>   static struct scmi_protocol_handle *ph;
>> @@ -174,6 +181,22 @@ static struct freq_attr *scmi_cpufreq_hw_attr[] = {
>>          NULL,
>>   };
>>
>> +static int scmi_limit_notify_cb(struct notifier_block *nb, unsigned long event, void *data)
>> +{
>> +       struct scmi_data *priv = container_of(nb, struct scmi_data, limit_notify_nb);
>> +       struct scmi_perf_limits_report *limit_notify = data;
>> +       struct cpufreq_policy *policy = priv->policy;
>> +       unsigned int limit_freq_khz;
>> +
>> +       limit_freq_khz = limit_notify->range_max_freq / HZ_PER_KHZ;
>> +
>> +       policy->max = clamp(limit_freq_khz, policy->cpuinfo.min_freq, policy->cpuinfo.max_freq);
>> +
>> +       cpufreq_update_pressure(policy);
> 
> I noticed your patch while looking for other things in the archive but
> I don't think this is the right way to do it.
> 
> cpufreq_update_pressure() aims to set to the scheduler the aggregation
> of all cappings set to cpufreq through the pm_qos and
> freq_qos_add_request(). Calling this function directly in scmi
> notification callback will overwrite the pm_qos aggregation. And at
> the opposite, any update of a pm_qos constraint will overwrite scmi
> notification. Instead you should better set a pm_qos constraint like
> others

Sure, I'll drop update_pressue and use the freq_qos_update_request to
update the policy->max_freq_req with the new policy->max.

-Sibi

> 
>> +
>> +       return NOTIFY_OK;
>> +}
>> +
>>   static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>>   {
>>          int ret, nr_opp, domain;
>> @@ -181,6 +204,7 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>>          struct device *cpu_dev;
>>          struct scmi_data *priv;
>>          struct cpufreq_frequency_table *freq_table;
>> +       struct scmi_cpufreq_driver_data *data = cpufreq_get_driver_data();
>>
>>          cpu_dev = get_cpu_device(policy->cpu);
>>          if (!cpu_dev) {
>> @@ -294,6 +318,17 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>>                  }
>>          }
>>
>> +       priv->limit_notify_nb.notifier_call = scmi_limit_notify_cb;
>> +       ret = data->handle->notify_ops->devm_event_notifier_register(data->sdev, SCMI_PROTOCOL_PERF,
>> +                                                       SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
>> +                                                       &domain,
>> +                                                       &priv->limit_notify_nb);
>> +       if (ret)
>> +               dev_warn(cpu_dev,
>> +                        "failed to register for limits change notifier for domain %d\n", domain);
>> +
>> +       priv->policy = policy;
>> +
>>          return 0;
>>
>>   out_free_opp:
>> @@ -366,12 +401,21 @@ static int scmi_cpufreq_probe(struct scmi_device *sdev)
>>          int ret;
>>          struct device *dev = &sdev->dev;
>>          const struct scmi_handle *handle;
>> +       struct scmi_cpufreq_driver_data *data;
>>
>>          handle = sdev->handle;
>>
>>          if (!handle)
>>                  return -ENODEV;
>>
>> +       data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
>> +       if (!data)
>> +               return -ENOMEM;
>> +
>> +       data->sdev = sdev;
>> +       data->handle = handle;
>> +       scmi_cpufreq_driver.driver_data = data;
>> +
>>          perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
>>          if (IS_ERR(perf_ops))
>>                  return PTR_ERR(perf_ops);
>> --
>> 2.34.1
>>
>>