[PATCH v2 0/2] PM / devfreq: Add dev_pm_qos support

[PATCH v2 0/2] PM / devfreq: Add dev_pm_qos support

[Leonard Crestez]

Add dev_pm_qos notifiers to devfreq core in order to support frequency
limits via dev_pm_qos_add_request.

Unlike the rest of devfreq the dev_pm_qos frequency is measured in kHz,
this is consistent with current dev_pm_qos usage for cpufreq and
allows frequencies above 2Ghz (pm_qos expresses limits as s32).

Like with cpufreq the handling of min_freq/max_freq is moved to the
dev_pm_qos mechanism. Constraints from userspace are no longer clamped on
store, instead all values can be written and we only check against OPPs in a
new devfreq_get_freq_range function. This is consistent with the design of
dev_pm_qos.

Notifiers from pm_qos are executed under a single global dev_pm_qos_mtx and
need to take devfreq->lock, this means that calls into dev_pm_qos while holding
devfreq->lock are not allowed (lockdep warns about possible deadlocks).

Fix this by only adding the qos request and notifiers after devfreq->lock is
released inside devfreq_add_device. In theory this means sysfs writes
are possible before the min/max requests are initialized so we guard
against that explictly. The dev_pm_qos_update_request function would
otherwise print a big WARN splat.

This series depends on recently accepted series restoring
DEV_PM_QOS_MIN/MAX_FREQUENCY inside the pm core:

	https://patchwork.kernel.org/cover/11262633/

It would be great for this to get into 5.5-rc1

---
Changes since RFC v1:
* Trim cover letter
* Drop RFC since DEV_PM_QOS_MIN/MAX_FREQUENCY was restored
* Collect Acks.
* No code changes
Link to v1: https://patchwork.kernel.org/cover/11252415/

Changes since "big version" v10:
* Drop accepted cleanups
* Work with current locking approach (split cleanups into other series)
* Drop acks and deliberately relabel as a new series. It still incorporates
most previous discussion but takes a different approach to locking.
* Don't print errors if devfreq_dev_release is called on error cleanup from
devfreq_add_device, just accept that requests and notifiers might not be
registered yet. I wish dev_pm_qos cleanups behaved like standard "kfree" and
silently did nothing when there's nothing to be done.
Link to v10: https://patchwork.kernel.org/project/linux-arm-kernel/list/?series=196443

Leonard Crestez (2):
  PM / devfreq: Add PM QoS support
  PM / devfreq: Use PM QoS for sysfs min/max_freq

 drivers/devfreq/devfreq.c | 151 ++++++++++++++++++++++++++++++++++----
 include/linux/devfreq.h   |  14 +++-
 2 files changed, 145 insertions(+), 20 deletions(-)

-- 
2.17.1


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[PATCH v2 1/2] PM / devfreq: Add PM QoS support

[Leonard Crestez]

Register notifiers with the PM QoS framework in order to respond to
requests for DEV_PM_QOS_MIN_FREQUENCY and DEV_PM_QOS_MAX_FREQUENCY.

No notifiers are added by this patch but PM QoS constraints can be
imposed externally (for example from other devices).

Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
---
 drivers/devfreq/devfreq.c | 77 +++++++++++++++++++++++++++++++++++++++
 include/linux/devfreq.h   |  5 +++
 2 files changed, 82 insertions(+)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index bdeb4189c978..e8b943fc4259 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -22,15 +22,18 @@
 #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 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
@@ -109,10 +112,11 @@ static unsigned long find_available_max_freq(struct devfreq *devfreq)
 static void get_freq_range(struct devfreq *devfreq,
 			   unsigned long *min_freq,
 			   unsigned long *max_freq)
 {
 	unsigned long *freq_table = devfreq->profile->freq_table;
+	s32 qos_min_freq, qos_max_freq;
 
 	lockdep_assert_held(&devfreq->lock);
 
 	/*
 	 * Initialize minimum/maximum frequency from freq table.
@@ -125,10 +129,20 @@ static void get_freq_range(struct devfreq *devfreq,
 	} else {
 		*min_freq = freq_table[devfreq->profile->max_state - 1];
 		*max_freq = freq_table[0];
 	}
 
+	/* Apply constraints from PM QoS */
+	qos_min_freq = dev_pm_qos_read_value(devfreq->dev.parent,
+					     DEV_PM_QOS_MIN_FREQUENCY);
+	qos_max_freq = dev_pm_qos_read_value(devfreq->dev.parent,
+					     DEV_PM_QOS_MAX_FREQUENCY);
+	*min_freq = max(*min_freq, (unsigned long)HZ_PER_KHZ * qos_min_freq);
+	if (qos_max_freq != PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE)
+		*max_freq = min(*max_freq,
+				(unsigned long)HZ_PER_KHZ * qos_max_freq);
+
 	/* Apply constraints from sysfs */
 	*min_freq = max(*min_freq, devfreq->min_freq);
 	*max_freq = min(*max_freq, devfreq->max_freq);
 
 	/* Apply constraints from OPP interface */
@@ -624,24 +638,75 @@ static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
 			err);
 
 	return NOTIFY_OK;
 }
 
+/**
+ * qos_notifier_call() - Common handler for QoS constraints.
+ * @devfreq:    the devfreq instance.
+ */
+static int qos_notifier_call(struct devfreq *devfreq)
+{
+	int err;
+
+	mutex_lock(&devfreq->lock);
+	err = update_devfreq(devfreq);
+	mutex_unlock(&devfreq->lock);
+	if (err)
+		dev_err(devfreq->dev.parent,
+			"failed to update frequency from PM QoS (%d)\n",
+			err);
+
+	return NOTIFY_OK;
+}
+
+/**
+ * qos_min_notifier_call() - Callback for QoS min_freq changes.
+ * @nb:		Should be devfreq->nb_min
+ */
+static int qos_min_notifier_call(struct notifier_block *nb,
+					 unsigned long val, void *ptr)
+{
+	return qos_notifier_call(container_of(nb, struct devfreq, nb_min));
+}
+
+/**
+ * qos_max_notifier_call() - Callback for QoS max_freq changes.
+ * @nb:		Should be devfreq->nb_max
+ */
+static int qos_max_notifier_call(struct notifier_block *nb,
+					 unsigned long val, void *ptr)
+{
+	return qos_notifier_call(container_of(nb, struct devfreq, nb_max));
+}
+
 /**
  * devfreq_dev_release() - Callback for struct device to release the device.
  * @dev:	the devfreq device
  *
  * Remove devfreq from the list and release its resources.
  */
 static void devfreq_dev_release(struct device *dev)
 {
 	struct devfreq *devfreq = to_devfreq(dev);
+	int err;
 
 	mutex_lock(&devfreq_list_lock);
 	list_del(&devfreq->node);
 	mutex_unlock(&devfreq_list_lock);
 
+	err = dev_pm_qos_remove_notifier(devfreq->dev.parent, &devfreq->nb_max,
+					 DEV_PM_QOS_MAX_FREQUENCY);
+	if (err && err != -ENOENT)
+		dev_warn(dev->parent,
+			"Failed to remove max_freq notifier: %d\n", err);
+	err = dev_pm_qos_remove_notifier(devfreq->dev.parent, &devfreq->nb_min,
+					 DEV_PM_QOS_MIN_FREQUENCY);
+	if (err && err != -ENOENT)
+		dev_warn(dev->parent,
+			"Failed to remove min_freq notifier: %d\n", err);
+
 	if (devfreq->profile->exit)
 		devfreq->profile->exit(devfreq->dev.parent);
 
 	mutex_destroy(&devfreq->lock);
 	kfree(devfreq);
@@ -760,10 +825,22 @@ struct devfreq *devfreq_add_device(struct device *dev,
 
 	srcu_init_notifier_head(&devfreq->transition_notifier_list);
 
 	mutex_unlock(&devfreq->lock);
 
+	devfreq->nb_min.notifier_call = 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 = 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",
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index 2bae9ed3c783..8b92ccbd1962 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;
-- 
2.17.1


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[PATCH v2 2/2] PM / devfreq: Use PM QoS for sysfs min/max_freq

[Leonard Crestez]

Switch the handling of min_freq and max_freq from sysfs to use the
dev_pm_qos_request interface.

Since PM QoS handles frequencies as kHz this change reduces the
precision of min_freq and max_freq. This shouldn't introduce problems
because frequencies which are not an integer number of kHz are likely
not an integer number of Hz either.

Try to ensure compatibility by rounding min values down and rounding
max values up.

Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
---
 drivers/devfreq/devfreq.c | 76 ++++++++++++++++++++++++++++++---------
 include/linux/devfreq.h   |  9 ++---
 2 files changed, 64 insertions(+), 21 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index e8b943fc4259..bcb286509547 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -139,14 +139,10 @@ static void get_freq_range(struct devfreq *devfreq,
 	*min_freq = max(*min_freq, (unsigned long)HZ_PER_KHZ * qos_min_freq);
 	if (qos_max_freq != PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE)
 		*max_freq = min(*max_freq,
 				(unsigned long)HZ_PER_KHZ * qos_max_freq);
 
-	/* Apply constraints from sysfs */
-	*min_freq = max(*min_freq, devfreq->min_freq);
-	*max_freq = min(*max_freq, devfreq->max_freq);
-
 	/* Apply constraints from OPP interface */
 	*min_freq = max(*min_freq, devfreq->scaling_min_freq);
 	*max_freq = min(*max_freq, devfreq->scaling_max_freq);
 
 	if (*min_freq > *max_freq)
@@ -703,10 +699,23 @@ static void devfreq_dev_release(struct device *dev)
 					 DEV_PM_QOS_MIN_FREQUENCY);
 	if (err && err != -ENOENT)
 		dev_warn(dev->parent,
 			"Failed to remove min_freq notifier: %d\n", err);
 
+	if (dev_pm_qos_request_active(&devfreq->user_max_freq_req)) {
+		err = dev_pm_qos_remove_request(&devfreq->user_max_freq_req);
+		if (err)
+			dev_warn(dev->parent,
+				"Failed to remove max_freq request: %d\n", err);
+	}
+	if (dev_pm_qos_request_active(&devfreq->user_min_freq_req)) {
+		err = dev_pm_qos_remove_request(&devfreq->user_min_freq_req);
+		if (err)
+			dev_warn(dev->parent,
+				"Failed to remove min_freq request: %d\n", err);
+	}
+
 	if (devfreq->profile->exit)
 		devfreq->profile->exit(devfreq->dev.parent);
 
 	mutex_destroy(&devfreq->lock);
 	kfree(devfreq);
@@ -776,19 +785,17 @@ struct devfreq *devfreq_add_device(struct device *dev,
 	if (!devfreq->scaling_min_freq) {
 		mutex_unlock(&devfreq->lock);
 		err = -EINVAL;
 		goto err_dev;
 	}
-	devfreq->min_freq = devfreq->scaling_min_freq;
 
 	devfreq->scaling_max_freq = find_available_max_freq(devfreq);
 	if (!devfreq->scaling_max_freq) {
 		mutex_unlock(&devfreq->lock);
 		err = -EINVAL;
 		goto err_dev;
 	}
-	devfreq->max_freq = devfreq->scaling_max_freq;
 
 	devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
 	atomic_set(&devfreq->suspend_count, 0);
 
 	dev_set_name(&devfreq->dev, "devfreq%d",
@@ -825,10 +832,20 @@ struct devfreq *devfreq_add_device(struct device *dev,
 
 	srcu_init_notifier_head(&devfreq->transition_notifier_list);
 
 	mutex_unlock(&devfreq->lock);
 
+	err = dev_pm_qos_add_request(dev, &devfreq->user_min_freq_req,
+				     DEV_PM_QOS_MIN_FREQUENCY, 0);
+	if (err < 0)
+		goto err_devfreq;
+	err = dev_pm_qos_add_request(dev, &devfreq->user_max_freq_req,
+				     DEV_PM_QOS_MAX_FREQUENCY,
+				     PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE);
+	if (err < 0)
+		goto err_devfreq;
+
 	devfreq->nb_min.notifier_call = 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;
@@ -1418,18 +1435,26 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
 {
 	struct devfreq *df = to_devfreq(dev);
 	unsigned long value;
 	int ret;
 
+	/*
+	 * Protect against theoretical sysfs writes between
+	 * device_add and dev_pm_qos_add_request
+	 */
+	if (!dev_pm_qos_request_active(&df->user_min_freq_req))
+		return -EINVAL;
+
 	ret = sscanf(buf, "%lu", &value);
 	if (ret != 1)
 		return -EINVAL;
 
-	mutex_lock(&df->lock);
-	df->min_freq = value;
-	update_devfreq(df);
-	mutex_unlock(&df->lock);
+	/* Round down to kHz for PM QoS */
+	ret = dev_pm_qos_update_request(&df->user_min_freq_req,
+					value / HZ_PER_KHZ);
+	if (ret < 0)
+		return ret;
 
 	return count;
 }
 
 static ssize_t min_freq_show(struct device *dev, struct device_attribute *attr,
@@ -1450,22 +1475,39 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
 {
 	struct devfreq *df = to_devfreq(dev);
 	unsigned long value;
 	int ret;
 
+	/*
+	 * Protect against theoretical sysfs writes between
+	 * device_add and dev_pm_qos_add_request
+	 */
+	if (!dev_pm_qos_request_active(&df->user_max_freq_req))
+		return -EINVAL;
+
 	ret = sscanf(buf, "%lu", &value);
 	if (ret != 1)
 		return -EINVAL;
 
-	mutex_lock(&df->lock);
-
-	if (!value)
-		value = ULONG_MAX;
+	/*
+	 * PM QoS frequencies are in kHz so we need to convert. Convert by
+	 * rounding upwards so that the acceptable interval never shrinks.
+	 *
+	 * For example if the user writes "666666666" to sysfs this value will
+	 * be converted to 666667 kHz and back to 666667000 Hz before an OPP
+	 * lookup, this ensures that an OPP of 666666666Hz is still accepted.
+	 *
+	 * A value of zero means "no limit".
+	 */
+	if (value)
+		value = DIV_ROUND_UP(value, HZ_PER_KHZ);
+	else
+		value = PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE;
 
-	df->max_freq = value;
-	update_devfreq(df);
-	mutex_unlock(&df->lock);
+	ret = dev_pm_qos_update_request(&df->user_max_freq_req, value);
+	if (ret < 0)
+		return ret;
 
 	return count;
 }
 static DEVICE_ATTR_RW(min_freq);
 
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index 8b92ccbd1962..fb376b5b7281 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -11,10 +11,11 @@
 #define __LINUX_DEVFREQ_H__
 
 #include <linux/device.h>
 #include <linux/notifier.h>
 #include <linux/pm_opp.h>
+#include <linux/pm_qos.h>
 
 #define DEVFREQ_NAME_LEN 16
 
 /* DEVFREQ governor name */
 #define DEVFREQ_GOV_SIMPLE_ONDEMAND	"simple_ondemand"
@@ -121,12 +122,12 @@ struct devfreq_dev_profile {
  *		devfreq.nb to the corresponding register notifier call chain.
  * @work:	delayed work for load monitoring.
  * @previous_freq:	previously configured frequency value.
  * @data:	Private data of the governor. The devfreq framework does not
  *		touch this.
- * @min_freq:	Limit minimum frequency requested by user (0: none)
- * @max_freq:	Limit maximum frequency requested by user (0: none)
+ * @user_min_freq_req:	PM QoS minimum frequency request from user (via sysfs)
+ * @user_max_freq_req:	PM QoS maximum frequency request from user (via sysfs)
  * @scaling_min_freq:	Limit minimum frequency requested by OPP interface
  * @scaling_max_freq:	Limit maximum frequency requested by OPP interface
  * @stop_polling:	 devfreq polling status of a device.
  * @suspend_freq:	 frequency of a device set during suspend phase.
  * @resume_freq:	 frequency of a device set in resume phase.
@@ -161,12 +162,12 @@ struct devfreq {
 	unsigned long previous_freq;
 	struct devfreq_dev_status last_status;
 
 	void *data; /* private data for governors */
 
-	unsigned long min_freq;
-	unsigned long max_freq;
+	struct dev_pm_qos_request user_min_freq_req;
+	struct dev_pm_qos_request user_max_freq_req;
 	unsigned long scaling_min_freq;
 	unsigned long scaling_max_freq;
 	bool stop_polling;
 
 	unsigned long suspend_freq;
-- 
2.17.1


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Re: [PATCH v2 0/2] PM / devfreq: Add dev_pm_qos support

[Rafael J. Wysocki]

On Thu, Dec 5, 2019 at 11:05 AM Leonard Crestez <leonard.crestez@nxp.com> wrote:
>
> Add dev_pm_qos notifiers to devfreq core in order to support frequency
> limits via dev_pm_qos_add_request.
>
> Unlike the rest of devfreq the dev_pm_qos frequency is measured in kHz,
> this is consistent with current dev_pm_qos usage for cpufreq and
> allows frequencies above 2Ghz (pm_qos expresses limits as s32).
>
> Like with cpufreq the handling of min_freq/max_freq is moved to the
> dev_pm_qos mechanism. Constraints from userspace are no longer clamped on
> store, instead all values can be written and we only check against OPPs in a
> new devfreq_get_freq_range function. This is consistent with the design of
> dev_pm_qos.
>
> Notifiers from pm_qos are executed under a single global dev_pm_qos_mtx and
> need to take devfreq->lock, this means that calls into dev_pm_qos while holding
> devfreq->lock are not allowed (lockdep warns about possible deadlocks).
>
> Fix this by only adding the qos request and notifiers after devfreq->lock is
> released inside devfreq_add_device. In theory this means sysfs writes
> are possible before the min/max requests are initialized so we guard
> against that explictly. The dev_pm_qos_update_request function would
> otherwise print a big WARN splat.
>
> This series depends on recently accepted series restoring
> DEV_PM_QOS_MIN/MAX_FREQUENCY inside the pm core:
>
>         https://patchwork.kernel.org/cover/11262633/
>
> It would be great for this to get into 5.5-rc1

Not at this point.  The earliest realistic target can be -rc2.

Does this still depend on anything which has not been included into
the Linus' tree to date?

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Re: [PATCH v2 0/2] PM / devfreq: Add dev_pm_qos support

[Leonard Crestez]

On 2019-12-05 12:13 PM, Rafael J. Wysocki wrote:
> On Thu, Dec 5, 2019 at 11:05 AM Leonard Crestez <leonard.crestez@nxp.com> wrote:
>>
>> Add dev_pm_qos notifiers to devfreq core in order to support frequency
>> limits via dev_pm_qos_add_request.
>>
>> Unlike the rest of devfreq the dev_pm_qos frequency is measured in kHz,
>> this is consistent with current dev_pm_qos usage for cpufreq and
>> allows frequencies above 2Ghz (pm_qos expresses limits as s32).
>>
>> Like with cpufreq the handling of min_freq/max_freq is moved to the
>> dev_pm_qos mechanism. Constraints from userspace are no longer clamped on
>> store, instead all values can be written and we only check against OPPs in a
>> new devfreq_get_freq_range function. This is consistent with the design of
>> dev_pm_qos.
>>
>> Notifiers from pm_qos are executed under a single global dev_pm_qos_mtx and
>> need to take devfreq->lock, this means that calls into dev_pm_qos while holding
>> devfreq->lock are not allowed (lockdep warns about possible deadlocks).
>>
>> Fix this by only adding the qos request and notifiers after devfreq->lock is
>> released inside devfreq_add_device. In theory this means sysfs writes
>> are possible before the min/max requests are initialized so we guard
>> against that explictly. The dev_pm_qos_update_request function would
>> otherwise print a big WARN splat.
>>
>> This series depends on recently accepted series restoring
>> DEV_PM_QOS_MIN/MAX_FREQUENCY inside the pm core:
>>
>>          https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchwork.kernel.org%2Fcover%2F11262633%2F&amp;data=02%7C01%7Cleonard.crestez%40nxp.com%7C265c079a936b4c2a9c6608d7796bbc16%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637111375932506745&amp;sdata=uI0if7aNnedxEsMlNQ4sCDOElVBxCp%2B%2BVGaeZC0DaMk%3D&amp;reserved=0
>>
>> It would be great for this to get into 5.5-rc1
> 
> Not at this point.  The earliest realistic target can be -rc2.
> 
> Does this still depend on anything which has not been included into
> the Linus' tree to date?

This series depends on DEV_PM_QOS_MIN/MAX_FREQUENCY and that's already 
in. It also depends on a few other patches from devfreq-next:

https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/commit/?h=devfreq-next&id=1d81785fd070088c952fd9f0d8cb4c47c192122b
https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/commit/?h=devfreq-next&id=a2b3d24b75036c44a5509e9ec3a5c14672e98c73
https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/commit/?h=devfreq-next&id=0f68bfe7d58dfb49972f93768f9fdd97ce205844

It doesn't currently apply on torvalds/master

There are some interconnect patches which depend on this for proper 
functionality but we can figure something out with icc maintainer.

* https://patchwork.kernel.org/cover/11244421/
* https://patchwork.kernel.org/patch/11153917/

I personally always test with linux-next so RC schedules don't affect me 
very much.

--
Regards,
Leonard

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Re: [PATCH v2 1/2] PM / devfreq: Add PM QoS support

[Matthias Kaehlcke]

On Thu, Dec 05, 2019 at 12:05:06PM +0200, Leonard Crestez wrote:
> Register notifiers with the PM QoS framework in order to respond to
> requests for DEV_PM_QOS_MIN_FREQUENCY and DEV_PM_QOS_MAX_FREQUENCY.
> 
> No notifiers are added by this patch but PM QoS constraints can be
> imposed externally (for example from other devices).
> 
> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
> Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
> ---
>  drivers/devfreq/devfreq.c | 77 +++++++++++++++++++++++++++++++++++++++
>  include/linux/devfreq.h   |  5 +++
>  2 files changed, 82 insertions(+)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index bdeb4189c978..e8b943fc4259 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -22,15 +22,18 @@
>  #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 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
> @@ -109,10 +112,11 @@ static unsigned long find_available_max_freq(struct devfreq *devfreq)
>  static void get_freq_range(struct devfreq *devfreq,
>  			   unsigned long *min_freq,
>  			   unsigned long *max_freq)
>  {
>  	unsigned long *freq_table = devfreq->profile->freq_table;
> +	s32 qos_min_freq, qos_max_freq;
>  
>  	lockdep_assert_held(&devfreq->lock);
>  
>  	/*
>  	 * Initialize minimum/maximum frequency from freq table.
> @@ -125,10 +129,20 @@ static void get_freq_range(struct devfreq *devfreq,
>  	} else {
>  		*min_freq = freq_table[devfreq->profile->max_state - 1];
>  		*max_freq = freq_table[0];
>  	}
>  
> +	/* Apply constraints from PM QoS */
> +	qos_min_freq = dev_pm_qos_read_value(devfreq->dev.parent,
> +					     DEV_PM_QOS_MIN_FREQUENCY);
> +	qos_max_freq = dev_pm_qos_read_value(devfreq->dev.parent,
> +					     DEV_PM_QOS_MAX_FREQUENCY);
> +	*min_freq = max(*min_freq, (unsigned long)HZ_PER_KHZ * qos_min_freq);
> +	if (qos_max_freq != PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE)

The condition shouldn't be needed anymore now that
PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE is S32_MAX and not -1.

> +		*max_freq = min(*max_freq,
> +				(unsigned long)HZ_PER_KHZ * qos_max_freq);
> +

Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Tested-by: Matthias Kaehlcke <mka@chromium.org>

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Re: [PATCH v2 2/2] PM / devfreq: Use PM QoS for sysfs min/max_freq

[Matthias Kaehlcke]

On Thu, Dec 05, 2019 at 12:05:07PM +0200, Leonard Crestez wrote:
> Switch the handling of min_freq and max_freq from sysfs to use the
> dev_pm_qos_request interface.
> 
> Since PM QoS handles frequencies as kHz this change reduces the
> precision of min_freq and max_freq. This shouldn't introduce problems
> because frequencies which are not an integer number of kHz are likely
> not an integer number of Hz either.
> 
> Try to ensure compatibility by rounding min values down and rounding
> max values up.
> 
> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
> Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
> ---
>  drivers/devfreq/devfreq.c | 76 ++++++++++++++++++++++++++++++---------
>  include/linux/devfreq.h   |  9 ++---
>  2 files changed, 64 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index e8b943fc4259..bcb286509547 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -139,14 +139,10 @@ static void get_freq_range(struct devfreq *devfreq,
>  	*min_freq = max(*min_freq, (unsigned long)HZ_PER_KHZ * qos_min_freq);
>  	if (qos_max_freq != PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE)
>  		*max_freq = min(*max_freq,
>  				(unsigned long)HZ_PER_KHZ * qos_max_freq);
>  
> -	/* Apply constraints from sysfs */
> -	*min_freq = max(*min_freq, devfreq->min_freq);
> -	*max_freq = min(*max_freq, devfreq->max_freq);
> -
>  	/* Apply constraints from OPP interface */
>  	*min_freq = max(*min_freq, devfreq->scaling_min_freq);
>  	*max_freq = min(*max_freq, devfreq->scaling_max_freq);
>  
>  	if (*min_freq > *max_freq)
> @@ -703,10 +699,23 @@ static void devfreq_dev_release(struct device *dev)
>  					 DEV_PM_QOS_MIN_FREQUENCY);
>  	if (err && err != -ENOENT)
>  		dev_warn(dev->parent,
>  			"Failed to remove min_freq notifier: %d\n", err);
>  
> +	if (dev_pm_qos_request_active(&devfreq->user_max_freq_req)) {
> +		err = dev_pm_qos_remove_request(&devfreq->user_max_freq_req);
> +		if (err)
> +			dev_warn(dev->parent,
> +				"Failed to remove max_freq request: %d\n", err);
> +	}
> +	if (dev_pm_qos_request_active(&devfreq->user_min_freq_req)) {
> +		err = dev_pm_qos_remove_request(&devfreq->user_min_freq_req);
> +		if (err)
> +			dev_warn(dev->parent,
> +				"Failed to remove min_freq request: %d\n", err);
> +	}
> +
>  	if (devfreq->profile->exit)
>  		devfreq->profile->exit(devfreq->dev.parent);
>  
>  	mutex_destroy(&devfreq->lock);
>  	kfree(devfreq);
> @@ -776,19 +785,17 @@ struct devfreq *devfreq_add_device(struct device *dev,
>  	if (!devfreq->scaling_min_freq) {
>  		mutex_unlock(&devfreq->lock);
>  		err = -EINVAL;
>  		goto err_dev;
>  	}
> -	devfreq->min_freq = devfreq->scaling_min_freq;
>  
>  	devfreq->scaling_max_freq = find_available_max_freq(devfreq);
>  	if (!devfreq->scaling_max_freq) {
>  		mutex_unlock(&devfreq->lock);
>  		err = -EINVAL;
>  		goto err_dev;
>  	}
> -	devfreq->max_freq = devfreq->scaling_max_freq;
>  
>  	devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
>  	atomic_set(&devfreq->suspend_count, 0);
>  
>  	dev_set_name(&devfreq->dev, "devfreq%d",
> @@ -825,10 +832,20 @@ struct devfreq *devfreq_add_device(struct device *dev,
>  
>  	srcu_init_notifier_head(&devfreq->transition_notifier_list);
>  
>  	mutex_unlock(&devfreq->lock);
>  
> +	err = dev_pm_qos_add_request(dev, &devfreq->user_min_freq_req,
> +				     DEV_PM_QOS_MIN_FREQUENCY, 0);
> +	if (err < 0)
> +		goto err_devfreq;
> +	err = dev_pm_qos_add_request(dev, &devfreq->user_max_freq_req,
> +				     DEV_PM_QOS_MAX_FREQUENCY,
> +				     PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE);
> +	if (err < 0)
> +		goto err_devfreq;
> +
>  	devfreq->nb_min.notifier_call = 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;
> @@ -1418,18 +1435,26 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>  {
>  	struct devfreq *df = to_devfreq(dev);
>  	unsigned long value;
>  	int ret;
>  
> +	/*
> +	 * Protect against theoretical sysfs writes between
> +	 * device_add and dev_pm_qos_add_request
> +	 */
> +	if (!dev_pm_qos_request_active(&df->user_min_freq_req))
> +		return -EINVAL;

The error code -EINVAL is a bit misleading. I guess it's not super
important, especially since this is a very rare case. In case you
re-spin you could consider returning -EAGAIN ('Resource temporarily
unavailable') in this case from min/max_freq_store/show()

Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Tested-by: Matthias Kaehlcke <mka@chromium.org>

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Re: [PATCH v2 2/2] PM / devfreq: Use PM QoS for sysfs min/max_freq

[Chanwoo Choi]

On 12/6/19 3:02 AM, Matthias Kaehlcke wrote:
> On Thu, Dec 05, 2019 at 12:05:07PM +0200, Leonard Crestez wrote:
>> Switch the handling of min_freq and max_freq from sysfs to use the
>> dev_pm_qos_request interface.
>>
>> Since PM QoS handles frequencies as kHz this change reduces the
>> precision of min_freq and max_freq. This shouldn't introduce problems
>> because frequencies which are not an integer number of kHz are likely
>> not an integer number of Hz either.
>>
>> Try to ensure compatibility by rounding min values down and rounding
>> max values up.
>>
>> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
>> Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
>> ---
>>  drivers/devfreq/devfreq.c | 76 ++++++++++++++++++++++++++++++---------
>>  include/linux/devfreq.h   |  9 ++---
>>  2 files changed, 64 insertions(+), 21 deletions(-)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index e8b943fc4259..bcb286509547 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -139,14 +139,10 @@ static void get_freq_range(struct devfreq *devfreq,
>>  	*min_freq = max(*min_freq, (unsigned long)HZ_PER_KHZ * qos_min_freq);
>>  	if (qos_max_freq != PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE)
>>  		*max_freq = min(*max_freq,
>>  				(unsigned long)HZ_PER_KHZ * qos_max_freq);
>>  
>> -	/* Apply constraints from sysfs */
>> -	*min_freq = max(*min_freq, devfreq->min_freq);
>> -	*max_freq = min(*max_freq, devfreq->max_freq);
>> -
>>  	/* Apply constraints from OPP interface */
>>  	*min_freq = max(*min_freq, devfreq->scaling_min_freq);
>>  	*max_freq = min(*max_freq, devfreq->scaling_max_freq);
>>  
>>  	if (*min_freq > *max_freq)
>> @@ -703,10 +699,23 @@ static void devfreq_dev_release(struct device *dev)
>>  					 DEV_PM_QOS_MIN_FREQUENCY);
>>  	if (err && err != -ENOENT)
>>  		dev_warn(dev->parent,
>>  			"Failed to remove min_freq notifier: %d\n", err);
>>  
>> +	if (dev_pm_qos_request_active(&devfreq->user_max_freq_req)) {
>> +		err = dev_pm_qos_remove_request(&devfreq->user_max_freq_req);
>> +		if (err)
>> +			dev_warn(dev->parent,
>> +				"Failed to remove max_freq request: %d\n", err);
>> +	}
>> +	if (dev_pm_qos_request_active(&devfreq->user_min_freq_req)) {
>> +		err = dev_pm_qos_remove_request(&devfreq->user_min_freq_req);
>> +		if (err)
>> +			dev_warn(dev->parent,
>> +				"Failed to remove min_freq request: %d\n", err);
>> +	}
>> +
>>  	if (devfreq->profile->exit)
>>  		devfreq->profile->exit(devfreq->dev.parent);
>>  
>>  	mutex_destroy(&devfreq->lock);
>>  	kfree(devfreq);
>> @@ -776,19 +785,17 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>  	if (!devfreq->scaling_min_freq) {
>>  		mutex_unlock(&devfreq->lock);
>>  		err = -EINVAL;
>>  		goto err_dev;
>>  	}
>> -	devfreq->min_freq = devfreq->scaling_min_freq;
>>  
>>  	devfreq->scaling_max_freq = find_available_max_freq(devfreq);
>>  	if (!devfreq->scaling_max_freq) {
>>  		mutex_unlock(&devfreq->lock);
>>  		err = -EINVAL;
>>  		goto err_dev;
>>  	}
>> -	devfreq->max_freq = devfreq->scaling_max_freq;
>>  
>>  	devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
>>  	atomic_set(&devfreq->suspend_count, 0);
>>  
>>  	dev_set_name(&devfreq->dev, "devfreq%d",
>> @@ -825,10 +832,20 @@ struct devfreq *devfreq_add_device(struct device *dev,
>>  
>>  	srcu_init_notifier_head(&devfreq->transition_notifier_list);
>>  
>>  	mutex_unlock(&devfreq->lock);
>>  
>> +	err = dev_pm_qos_add_request(dev, &devfreq->user_min_freq_req,
>> +				     DEV_PM_QOS_MIN_FREQUENCY, 0);
>> +	if (err < 0)
>> +		goto err_devfreq;
>> +	err = dev_pm_qos_add_request(dev, &devfreq->user_max_freq_req,
>> +				     DEV_PM_QOS_MAX_FREQUENCY,
>> +				     PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE);
>> +	if (err < 0)
>> +		goto err_devfreq;
>> +
>>  	devfreq->nb_min.notifier_call = 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;
>> @@ -1418,18 +1435,26 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
>>  {
>>  	struct devfreq *df = to_devfreq(dev);
>>  	unsigned long value;
>>  	int ret;
>>  
>> +	/*
>> +	 * Protect against theoretical sysfs writes between
>> +	 * device_add and dev_pm_qos_add_request
>> +	 */
>> +	if (!dev_pm_qos_request_active(&df->user_min_freq_req))
>> +		return -EINVAL;
> 
> The error code -EINVAL is a bit misleading. I guess it's not super
> important, especially since this is a very rare case. In case you
> re-spin you could consider returning -EAGAIN ('Resource temporarily
> unavailable') in this case from min/max_freq_store/show()

I agree. -EAGAIN is better than -EINVAL. I'll change it by myself.

> 
> Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
> Tested-by: Matthias Kaehlcke <mka@chromium.org>
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

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Re: [PATCH v2 0/2] PM / devfreq: Add dev_pm_qos support

[Chanwoo Choi]

On 12/5/19 7:44 PM, Leonard Crestez wrote:
> On 2019-12-05 12:13 PM, Rafael J. Wysocki wrote:
>> On Thu, Dec 5, 2019 at 11:05 AM Leonard Crestez <leonard.crestez@nxp.com> wrote:
>>>
>>> Add dev_pm_qos notifiers to devfreq core in order to support frequency
>>> limits via dev_pm_qos_add_request.
>>>
>>> Unlike the rest of devfreq the dev_pm_qos frequency is measured in kHz,
>>> this is consistent with current dev_pm_qos usage for cpufreq and
>>> allows frequencies above 2Ghz (pm_qos expresses limits as s32).
>>>
>>> Like with cpufreq the handling of min_freq/max_freq is moved to the
>>> dev_pm_qos mechanism. Constraints from userspace are no longer clamped on
>>> store, instead all values can be written and we only check against OPPs in a
>>> new devfreq_get_freq_range function. This is consistent with the design of
>>> dev_pm_qos.
>>>
>>> Notifiers from pm_qos are executed under a single global dev_pm_qos_mtx and
>>> need to take devfreq->lock, this means that calls into dev_pm_qos while holding
>>> devfreq->lock are not allowed (lockdep warns about possible deadlocks).
>>>
>>> Fix this by only adding the qos request and notifiers after devfreq->lock is
>>> released inside devfreq_add_device. In theory this means sysfs writes
>>> are possible before the min/max requests are initialized so we guard
>>> against that explictly. The dev_pm_qos_update_request function would
>>> otherwise print a big WARN splat.
>>>
>>> This series depends on recently accepted series restoring
>>> DEV_PM_QOS_MIN/MAX_FREQUENCY inside the pm core:
>>>
>>>          https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchwork.kernel.org%2Fcover%2F11262633%2F&amp;data=02%7C01%7Cleonard.crestez%40nxp.com%7C265c079a936b4c2a9c6608d7796bbc16%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637111375932506745&amp;sdata=uI0if7aNnedxEsMlNQ4sCDOElVBxCp%2B%2BVGaeZC0DaMk%3D&amp;reserved=0
>>>
>>> It would be great for this to get into 5.5-rc1
>>
>> Not at this point.  The earliest realistic target can be -rc2.
>>
>> Does this still depend on anything which has not been included into
>> the Linus' tree to date?
> 
> This series depends on DEV_PM_QOS_MIN/MAX_FREQUENCY and that's already 
> in. It also depends on a few other patches from devfreq-next:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/commit/?h=devfreq-next&id=1d81785fd070088c952fd9f0d8cb4c47c192122b
> https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/commit/?h=devfreq-next&id=a2b3d24b75036c44a5509e9ec3a5c14672e98c73
> https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/commit/?h=devfreq-next&id=0f68bfe7d58dfb49972f93768f9fdd97ce205844

And this patch depends on patch[1] in order to prevent the merge conflict.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/commit/?h=devfreq-fixes&id=6306ad828b335ba967d2f3c2cbfdb84ebda46cb8

For sending the devfreq pm-qos features for rc2 period,
- "devfreq-fixes" branch contains the required patches for devfreq pm-qos feature.
- "devfreq-testing-pm-qos" branch contains the devfreq pm-qos feature based on devfreq-fixes branch.
  To prevent the build error, applied the following four patches picked from linux-pm.git.
	PM / QoS: Restore DEV_PM_QOS_MIN/MAX_FREQUENCYdevfreq-testing-pm-qos
	PM / QoS: Reorder pm_qos/freq_qos/dev_pm_qos structs
	PM / QoS: Initial kunit test
	PM / QoS: Redefine FREQ_QOS_MAX_DEFAULT_VALUE to S32_MAX
: https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/log/?h=devfreq-testing

After released the v5.5-rc1, I'll send the devfreq pm-qos patches.

> 
> It doesn't currently apply on torvalds/master
> 
> There are some interconnect patches which depend on this for proper 
> functionality but we can figure something out with icc maintainer.
> 
> * https://patchwork.kernel.org/cover/11244421/
> * https://patchwork.kernel.org/patch/11153917/
> 
> I personally always test with linux-next so RC schedules don't affect me 
> very much.
> 
> --
> Regards,
> Leonard
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

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Re: [PATCH v2 0/2] PM / devfreq: Add dev_pm_qos support

[Chanwoo Choi]

On 12/6/19 12:27 PM, Chanwoo Choi wrote:
> On 12/5/19 7:44 PM, Leonard Crestez wrote:
>> On 2019-12-05 12:13 PM, Rafael J. Wysocki wrote:
>>> On Thu, Dec 5, 2019 at 11:05 AM Leonard Crestez <leonard.crestez@nxp.com> wrote:
>>>>
>>>> Add dev_pm_qos notifiers to devfreq core in order to support frequency
>>>> limits via dev_pm_qos_add_request.
>>>>
>>>> Unlike the rest of devfreq the dev_pm_qos frequency is measured in kHz,
>>>> this is consistent with current dev_pm_qos usage for cpufreq and
>>>> allows frequencies above 2Ghz (pm_qos expresses limits as s32).
>>>>
>>>> Like with cpufreq the handling of min_freq/max_freq is moved to the
>>>> dev_pm_qos mechanism. Constraints from userspace are no longer clamped on
>>>> store, instead all values can be written and we only check against OPPs in a
>>>> new devfreq_get_freq_range function. This is consistent with the design of
>>>> dev_pm_qos.
>>>>
>>>> Notifiers from pm_qos are executed under a single global dev_pm_qos_mtx and
>>>> need to take devfreq->lock, this means that calls into dev_pm_qos while holding
>>>> devfreq->lock are not allowed (lockdep warns about possible deadlocks).
>>>>
>>>> Fix this by only adding the qos request and notifiers after devfreq->lock is
>>>> released inside devfreq_add_device. In theory this means sysfs writes
>>>> are possible before the min/max requests are initialized so we guard
>>>> against that explictly. The dev_pm_qos_update_request function would
>>>> otherwise print a big WARN splat.
>>>>
>>>> This series depends on recently accepted series restoring
>>>> DEV_PM_QOS_MIN/MAX_FREQUENCY inside the pm core:
>>>>
>>>>          https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchwork.kernel.org%2Fcover%2F11262633%2F&amp;data=02%7C01%7Cleonard.crestez%40nxp.com%7C265c079a936b4c2a9c6608d7796bbc16%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637111375932506745&amp;sdata=uI0if7aNnedxEsMlNQ4sCDOElVBxCp%2B%2BVGaeZC0DaMk%3D&amp;reserved=0
>>>>
>>>> It would be great for this to get into 5.5-rc1
>>>
>>> Not at this point.  The earliest realistic target can be -rc2.
>>>
>>> Does this still depend on anything which has not been included into
>>> the Linus' tree to date?
>>
>> This series depends on DEV_PM_QOS_MIN/MAX_FREQUENCY and that's already 
>> in. It also depends on a few other patches from devfreq-next:
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/commit/?h=devfreq-next&id=1d81785fd070088c952fd9f0d8cb4c47c192122b
>> https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/commit/?h=devfreq-next&id=a2b3d24b75036c44a5509e9ec3a5c14672e98c73
>> https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/commit/?h=devfreq-next&id=0f68bfe7d58dfb49972f93768f9fdd97ce205844
> 
> And this patch depends on patch[1] in order to prevent the merge conflict.
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/commit/?h=devfreq-fixes&id=6306ad828b335ba967d2f3c2cbfdb84ebda46cb8
> 
> For sending the devfreq pm-qos features for rc2 period,
> - "devfreq-fixes" branch contains the required patches for devfreq pm-qos feature.
> - "devfreq-testing-pm-qos" branch contains the devfreq pm-qos feature based on devfreq-fixes branch.
>   To prevent the build error, applied the following four patches picked from linux-pm.git.
> 	PM / QoS: Restore DEV_PM_QOS_MIN/MAX_FREQUENCYdevfreq-testing-pm-qos
> 	PM / QoS: Reorder pm_qos/freq_qos/dev_pm_qos structs
> 	PM / QoS: Initial kunit test
> 	PM / QoS: Redefine FREQ_QOS_MAX_DEFAULT_VALUE to S32_MAX
> : https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/log/?h=devfreq-testing

I'm sorry. I wrote the wrong branch name previously.
Write the correct url of "devfreq-testing-pm-qos" branch.
: https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/log/?h=devfreq-testing-pm-qos

> 
> After released the v5.5-rc1, I'll send the devfreq pm-qos patches.
> 
>>
>> It doesn't currently apply on torvalds/master
>>
>> There are some interconnect patches which depend on this for proper 
>> functionality but we can figure something out with icc maintainer.
>>
>> * https://patchwork.kernel.org/cover/11244421/
>> * https://patchwork.kernel.org/patch/11153917/
>>
>> I personally always test with linux-next so RC schedules don't affect me 
>> very much.
>>
>> --
>> Regards,
>> Leonard
>>
>>
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

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Re: [PATCH v2 1/2] PM / devfreq: Add PM QoS support

[Leonard Crestez]

On 05.12.2019 19:48, Matthias Kaehlcke wrote:
> On Thu, Dec 05, 2019 at 12:05:06PM +0200, Leonard Crestez wrote:
>> Register notifiers with the PM QoS framework in order to respond to
>> requests for DEV_PM_QOS_MIN_FREQUENCY and DEV_PM_QOS_MAX_FREQUENCY.
>>
>> No notifiers are added by this patch but PM QoS constraints can be
>> imposed externally (for example from other devices).
>>
>> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
>> Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
>> ---
>>   drivers/devfreq/devfreq.c | 77 +++++++++++++++++++++++++++++++++++++++
>>   include/linux/devfreq.h   |  5 +++
>>   2 files changed, 82 insertions(+)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index bdeb4189c978..e8b943fc4259 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -22,15 +22,18 @@
>>   #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 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
>> @@ -109,10 +112,11 @@ static unsigned long find_available_max_freq(struct devfreq *devfreq)
>>   static void get_freq_range(struct devfreq *devfreq,
>>   			   unsigned long *min_freq,
>>   			   unsigned long *max_freq)
>>   {
>>   	unsigned long *freq_table = devfreq->profile->freq_table;
>> +	s32 qos_min_freq, qos_max_freq;
>>   
>>   	lockdep_assert_held(&devfreq->lock);
>>   
>>   	/*
>>   	 * Initialize minimum/maximum frequency from freq table.
>> @@ -125,10 +129,20 @@ static void get_freq_range(struct devfreq *devfreq,
>>   	} else {
>>   		*min_freq = freq_table[devfreq->profile->max_state - 1];
>>   		*max_freq = freq_table[0];
>>   	}
>>   
>> +	/* Apply constraints from PM QoS */
>> +	qos_min_freq = dev_pm_qos_read_value(devfreq->dev.parent,
>> +					     DEV_PM_QOS_MIN_FREQUENCY);
>> +	qos_max_freq = dev_pm_qos_read_value(devfreq->dev.parent,
>> +					     DEV_PM_QOS_MAX_FREQUENCY);
>> +	*min_freq = max(*min_freq, (unsigned long)HZ_PER_KHZ * qos_min_freq);
>> +	if (qos_max_freq != PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE)
> 
> The condition shouldn't be needed anymore now that
> PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE is S32_MAX and not -1.

On 32bit architectures S32_MAX * 1000 will overflow so it makes sense to 
keep this. It would also be possible to use u64 for frequencies but most 
code doesn't do that.

It's very odd that OPP frequencies and clock rates are expressed in Hz, 
are there no 32bit chips that run at more than 2ghz and run into issues?

> 
> Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
> Tested-by: Matthias Kaehlcke <mka@chromium.org>

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