diff mbox series

[6/8] PM / devfreq: Add dev_pm_qos support

Message ID feab364d702ba62102f212b7d415d9f768159163.1568764439.git.leonard.crestez@nxp.com (mailing list archive)
State Superseded
Headers show
Series PM / devfreq: Add dev_pm_qos support | expand

Commit Message

Leonard Crestez Sept. 18, 2019, 12:18 a.m. UTC
Register notifiers with the pm_qos framework in order to respond to
requests for MIN_FREQUENCY and MAX_FREQUENCY.

Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
---
 drivers/devfreq/devfreq.c | 71 +++++++++++++++++++++++++++++++++++++++
 include/linux/devfreq.h   |  5 +++
 2 files changed, 76 insertions(+)

Comments

Matthias Kaehlcke Sept. 19, 2019, 7:12 p.m. UTC | #1
On Wed, Sep 18, 2019 at 03:18:25AM +0300, Leonard Crestez wrote:
> Register notifiers with the pm_qos framework in order to respond to
> requests for MIN_FREQUENCY and MAX_FREQUENCY.

To make it clear that this change on it's own is a NOP maybe add
something like "No constraints are added for now though.", as in
67d874c3b2c6 ("cpufreq: Register notifiers with the PM QoS framework")

> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
> ---
>  drivers/devfreq/devfreq.c | 71 +++++++++++++++++++++++++++++++++++++++
>  include/linux/devfreq.h   |  5 +++
>  2 files changed, 76 insertions(+)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 51a4179e2c69..d8d57318b12c 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -22,17 +22,20 @@
>  #include <linux/platform_device.h>
>  #include <linux/list.h>
>  #include <linux/printk.h>
>  #include <linux/hrtimer.h>
>  #include <linux/of.h>
> +#include <linux/pm_qos.h>
>  #include "governor.h"
>  
>  #define HZ_PER_KHZ 1000
>  
>  #define CREATE_TRACE_POINTS
>  #include <trace/events/devfreq.h>
>  
> +#define HZ_PER_KHZ	1000
> +
>  static struct class *devfreq_class;
>  
>  /*
>   * devfreq core provides delayed work based load monitoring helper
>   * functions. Governors can use these or can implement their own
> @@ -123,10 +126,16 @@ static void devfreq_get_freq_range(struct devfreq *devfreq,
>  	} else {
>  		*min_freq = freq_table[devfreq->profile->max_state - 1];
>  		*max_freq = freq_table[0];
>  	}
>  
> +	/* constraints from dev_pm_qos: */

nit: QoS constraints?

> +	*min_freq = max(*min_freq, HZ_PER_KHZ * (unsigned long)dev_pm_qos_read_value(
> +				devfreq->dev.parent, DEV_PM_QOS_MIN_FREQUENCY));
> +	*max_freq = min(*max_freq, HZ_PER_KHZ * (unsigned long)dev_pm_qos_read_value(
> +				devfreq->dev.parent, DEV_PM_QOS_MAX_FREQUENCY));
> +
>  	/* constraints from sysfs: */
>  	*min_freq = max(*min_freq, devfreq->min_freq);
>  	*max_freq = min(*max_freq, devfreq->max_freq);
>  
>  	/* constraints from opp interface: */
> @@ -605,10 +614,49 @@ static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
>  	mutex_unlock(&devfreq->lock);
>  
>  	return ret;
>  }
>  
> +/**
> + * devfreq_qos_notifier_call() - Common handler for qos freq changes.

nit: QoS

s/freq/constraint/ ?

> + * @devfreq:    the devfreq instance.
> + */
> +static int devfreq_qos_notifier_call(struct devfreq *devfreq)
> +{
> +	int ret;
> +
> +	mutex_lock(&devfreq->lock);
> +	ret = update_devfreq(devfreq);
> +	mutex_unlock(&devfreq->lock);
> +
> +	return ret;
> +}
> +
> +/**
> + * devfreq_qos_min_notifier_call() - Callback for qos min_freq changes.

nit: QoS

> + * @nb:		Should to be devfreq->nb_min

s/to//

> + */
> +static int devfreq_qos_min_notifier_call(struct notifier_block *nb,
> +					 unsigned long val, void *ptr)
> +{
> +	struct devfreq *devfreq = container_of(nb, struct devfreq, nb_min);
> +
> +	return devfreq_qos_notifier_call(devfreq);
> +}
> +
> +/**
> + * devfreq_qos_max_notifier_call() - Callback for qos min_freq changes.

nit: QoS

s/min/max/

> + * @nb:		Should to be devfreq->nb_max

s/to//

> + */
> +static int devfreq_qos_max_notifier_call(struct notifier_block *nb,
> +					 unsigned long val, void *ptr)
> +{
> +	struct devfreq *devfreq = container_of(nb, struct devfreq, nb_max);
> +
> +	return devfreq_qos_notifier_call(devfreq);
> +}
> +
>  /**
>   * devfreq_dev_release() - Callback for struct device to release the device.
>   * @dev:	the devfreq device
>   *
>   * Remove devfreq from the list and release its resources.
> @@ -619,10 +667,15 @@ static void devfreq_dev_release(struct device *dev)
>  
>  	mutex_lock(&devfreq_list_lock);
>  	list_del(&devfreq->node);
>  	mutex_unlock(&devfreq_list_lock);
>  
> +	dev_pm_qos_remove_notifier(devfreq->dev.parent, &devfreq->nb_max,
> +			DEV_PM_QOS_MAX_FREQUENCY);
> +	dev_pm_qos_remove_notifier(devfreq->dev.parent, &devfreq->nb_min,
> +			DEV_PM_QOS_MIN_FREQUENCY);
> +

mega-nit: removing 'max' then 'min' does things in reverse order as
during initialization, which is common practice. But since the order
here doesn't really matter I'd stick to the common min/max order,
might readers save a few milli-seconds wondering why 'max' comes first.

>  	if (devfreq->profile->exit)
>  		devfreq->profile->exit(devfreq->dev.parent);
>  
>  	mutex_destroy(&devfreq->lock);
>  	kfree(devfreq->time_in_state);
> @@ -732,10 +785,27 @@ struct devfreq *devfreq_add_device(struct device *dev,
>  	if (err) {
>  		put_device(&devfreq->dev);
>  		goto err_out;
>  	}
>  
> +	/*
> +	 * Register notifiers for updates to min_freq/max_freq after device is

nit: min/max_freq?

> +	 * initialized (and we can handle notifications) but before the governor
> +	 * is started (which should do an initial enforcement of constraints)
> +	 */
> +	devfreq->nb_min.notifier_call = devfreq_qos_min_notifier_call;
> +	err = dev_pm_qos_add_notifier(devfreq->dev.parent, &devfreq->nb_min,
> +				      DEV_PM_QOS_MIN_FREQUENCY);
> +	if (err)
> +		goto err_devfreq;

IIUC you rely on the notifiers being removed by
devfreq_dev_release(). Does dev_pm_qos_remove_notifier() behave
gracefully if the notifier is not initialized/added or do we need
to use BLOCKING_NOTIFIER_INIT() or similar?
diff mbox series

Patch

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 51a4179e2c69..d8d57318b12c 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -22,17 +22,20 @@ 
 #include <linux/platform_device.h>
 #include <linux/list.h>
 #include <linux/printk.h>
 #include <linux/hrtimer.h>
 #include <linux/of.h>
+#include <linux/pm_qos.h>
 #include "governor.h"
 
 #define HZ_PER_KHZ 1000
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/devfreq.h>
 
+#define HZ_PER_KHZ	1000
+
 static struct class *devfreq_class;
 
 /*
  * devfreq core provides delayed work based load monitoring helper
  * functions. Governors can use these or can implement their own
@@ -123,10 +126,16 @@  static void devfreq_get_freq_range(struct devfreq *devfreq,
 	} else {
 		*min_freq = freq_table[devfreq->profile->max_state - 1];
 		*max_freq = freq_table[0];
 	}
 
+	/* constraints from dev_pm_qos: */
+	*min_freq = max(*min_freq, HZ_PER_KHZ * (unsigned long)dev_pm_qos_read_value(
+				devfreq->dev.parent, DEV_PM_QOS_MIN_FREQUENCY));
+	*max_freq = min(*max_freq, HZ_PER_KHZ * (unsigned long)dev_pm_qos_read_value(
+				devfreq->dev.parent, DEV_PM_QOS_MAX_FREQUENCY));
+
 	/* constraints from sysfs: */
 	*min_freq = max(*min_freq, devfreq->min_freq);
 	*max_freq = min(*max_freq, devfreq->max_freq);
 
 	/* constraints from opp interface: */
@@ -605,10 +614,49 @@  static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
 	mutex_unlock(&devfreq->lock);
 
 	return ret;
 }
 
+/**
+ * devfreq_qos_notifier_call() - Common handler for qos freq changes.
+ * @devfreq:    the devfreq instance.
+ */
+static int devfreq_qos_notifier_call(struct devfreq *devfreq)
+{
+	int ret;
+
+	mutex_lock(&devfreq->lock);
+	ret = update_devfreq(devfreq);
+	mutex_unlock(&devfreq->lock);
+
+	return ret;
+}
+
+/**
+ * devfreq_qos_min_notifier_call() - Callback for qos min_freq changes.
+ * @nb:		Should to be devfreq->nb_min
+ */
+static int devfreq_qos_min_notifier_call(struct notifier_block *nb,
+					 unsigned long val, void *ptr)
+{
+	struct devfreq *devfreq = container_of(nb, struct devfreq, nb_min);
+
+	return devfreq_qos_notifier_call(devfreq);
+}
+
+/**
+ * devfreq_qos_max_notifier_call() - Callback for qos min_freq changes.
+ * @nb:		Should to be devfreq->nb_max
+ */
+static int devfreq_qos_max_notifier_call(struct notifier_block *nb,
+					 unsigned long val, void *ptr)
+{
+	struct devfreq *devfreq = container_of(nb, struct devfreq, nb_max);
+
+	return devfreq_qos_notifier_call(devfreq);
+}
+
 /**
  * devfreq_dev_release() - Callback for struct device to release the device.
  * @dev:	the devfreq device
  *
  * Remove devfreq from the list and release its resources.
@@ -619,10 +667,15 @@  static void devfreq_dev_release(struct device *dev)
 
 	mutex_lock(&devfreq_list_lock);
 	list_del(&devfreq->node);
 	mutex_unlock(&devfreq_list_lock);
 
+	dev_pm_qos_remove_notifier(devfreq->dev.parent, &devfreq->nb_max,
+			DEV_PM_QOS_MAX_FREQUENCY);
+	dev_pm_qos_remove_notifier(devfreq->dev.parent, &devfreq->nb_min,
+			DEV_PM_QOS_MIN_FREQUENCY);
+
 	if (devfreq->profile->exit)
 		devfreq->profile->exit(devfreq->dev.parent);
 
 	mutex_destroy(&devfreq->lock);
 	kfree(devfreq->time_in_state);
@@ -732,10 +785,27 @@  struct devfreq *devfreq_add_device(struct device *dev,
 	if (err) {
 		put_device(&devfreq->dev);
 		goto err_out;
 	}
 
+	/*
+	 * Register notifiers for updates to min_freq/max_freq after device is
+	 * initialized (and we can handle notifications) but before the governor
+	 * is started (which should do an initial enforcement of constraints)
+	 */
+	devfreq->nb_min.notifier_call = devfreq_qos_min_notifier_call;
+	err = dev_pm_qos_add_notifier(devfreq->dev.parent, &devfreq->nb_min,
+				      DEV_PM_QOS_MIN_FREQUENCY);
+	if (err)
+		goto err_devfreq;
+
+	devfreq->nb_max.notifier_call = devfreq_qos_max_notifier_call;
+	err = dev_pm_qos_add_notifier(devfreq->dev.parent, &devfreq->nb_max,
+				      DEV_PM_QOS_MAX_FREQUENCY);
+	if (err)
+		goto err_devfreq;
+
 	mutex_lock(&devfreq_list_lock);
 
 	governor = try_then_request_governor(devfreq->governor_name);
 	if (IS_ERR(governor)) {
 		dev_err(dev, "%s: Unable to find governor for the device\n",
@@ -759,10 +829,11 @@  struct devfreq *devfreq_add_device(struct device *dev,
 
 	return devfreq;
 
 err_init:
 	mutex_unlock(&devfreq_list_lock);
+err_devfreq:
 	devfreq_remove_device(devfreq);
 	return ERR_PTR(err);
 err_dev:
 	kfree(devfreq->time_in_state);
 	kfree(devfreq->trans_table);
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index c3cbc15fdf08..dac0dffeabb4 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -134,10 +134,12 @@  struct devfreq_dev_profile {
  * @total_trans:	Number of devfreq transitions
  * @trans_table:	Statistics of devfreq transitions
  * @time_in_state:	Statistics of devfreq states
  * @last_stat_updated:	The last time stat updated
  * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
+ * @nb_min:		Notifier block for DEV_PM_QOS_MIN_FREQUENCY
+ * @nb_max:		Notifier block for DEV_PM_QOS_MAX_FREQUENCY
  *
  * This structure stores the devfreq information for a give device.
  *
  * Note that when a governor accesses entries in struct devfreq in its
  * functions except for the context of callbacks defined in struct
@@ -176,10 +178,13 @@  struct devfreq {
 	unsigned int *trans_table;
 	unsigned long *time_in_state;
 	unsigned long last_stat_updated;
 
 	struct srcu_notifier_head transition_notifier_list;
+
+	struct notifier_block nb_min;
+	struct notifier_block nb_max;
 };
 
 struct devfreq_freqs {
 	unsigned long old;
 	unsigned long new;