[PATCH 2/2] PM / devfreq: Use exclusively PM QoS to determine frequency limits

[Matthias Kaehlcke <mka@chromium.org>]

Traditionally devfreq cooling devices dynamically disabled OPPs
that shouldn't be used because of thermal pressure. Devfreq cooling
devices now use PM QoS to set frequency limits, hence the devfreq
code dealing that deals with disabled OPPs can be removed.

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---

 drivers/devfreq/devfreq.c | 75 +++++----------------------------------
 include/linux/devfreq.h   |  4 ---
 2 files changed, 8 insertions(+), 71 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 57f6944d65a6..ec66e2c27cc4 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -73,34 +73,6 @@ static struct devfreq *find_device_devfreq(struct device *dev)
 	return ERR_PTR(-ENODEV);
 }
 
-static unsigned long find_available_min_freq(struct devfreq *devfreq)
-{
-	struct dev_pm_opp *opp;
-	unsigned long min_freq = 0;
-
-	opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &min_freq);
-	if (IS_ERR(opp))
-		min_freq = 0;
-	else
-		dev_pm_opp_put(opp);
-
-	return min_freq;
-}
-
-static unsigned long find_available_max_freq(struct devfreq *devfreq)
-{
-	struct dev_pm_opp *opp;
-	unsigned long max_freq = ULONG_MAX;
-
-	opp = dev_pm_opp_find_freq_floor(devfreq->dev.parent, &max_freq);
-	if (IS_ERR(opp))
-		max_freq = 0;
-	else
-		dev_pm_opp_put(opp);
-
-	return max_freq;
-}
-
 /**
  * get_freq_range() - Get the current freq range
  * @devfreq:	the devfreq instance
@@ -141,10 +113,6 @@ static void get_freq_range(struct devfreq *devfreq,
 		*max_freq = min(*max_freq,
 				(unsigned long)HZ_PER_KHZ * qos_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)
 		*min_freq = *max_freq;
 }
@@ -610,23 +578,10 @@ static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
 				 void *devp)
 {
 	struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
-	int err = -EINVAL;
+	int err;
 
 	mutex_lock(&devfreq->lock);
-
-	devfreq->scaling_min_freq = find_available_min_freq(devfreq);
-	if (!devfreq->scaling_min_freq)
-		goto out;
-
-	devfreq->scaling_max_freq = find_available_max_freq(devfreq);
-	if (!devfreq->scaling_max_freq) {
-		devfreq->scaling_max_freq = ULONG_MAX;
-		goto out;
-	}
-
 	err = update_devfreq(devfreq);
-
-out:
 	mutex_unlock(&devfreq->lock);
 	if (err)
 		dev_err(devfreq->dev.parent,
@@ -781,19 +736,15 @@ struct devfreq *devfreq_add_device(struct device *dev,
 		mutex_lock(&devfreq->lock);
 	}
 
-	devfreq->scaling_min_freq = find_available_min_freq(devfreq);
-	if (!devfreq->scaling_min_freq) {
-		mutex_unlock(&devfreq->lock);
-		err = -EINVAL;
+	err = dev_pm_qos_add_request(dev, &devfreq->user_min_freq_req,
+				     DEV_PM_QOS_MIN_FREQUENCY, 0);
+	if (err < 0)
 		goto err_dev;
-	}
-
-	devfreq->scaling_max_freq = find_available_max_freq(devfreq);
-	if (!devfreq->scaling_max_freq) {
-		mutex_unlock(&devfreq->lock);
-		err = -EINVAL;
+	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_dev;
-	}
 
 	devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
 	atomic_set(&devfreq->suspend_count, 0);
@@ -834,16 +785,6 @@ struct devfreq *devfreq_add_device(struct device *dev,
 
 	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);
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index fb376b5b7281..cb75f23ad2f4 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -126,8 +126,6 @@ struct devfreq_dev_profile {
  *		touch this.
  * @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.
@@ -166,8 +164,6 @@ struct devfreq {
 
 	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;
-- 
2.25.0.rc1.283.g88dfdc4193-goog