PM / devfreq: Register devfreq as a cooling device on demand

The devfreq core code is able to register the devfreq device as a cooling device if the 'is_cooling_device' flag is set in the profile.

Use this flag and remove the cooling device registering code.

Tested on rock960.

Signed-off-by Daniel Lezcano <[email protected]>

---
  drivers/gpu/drm/panfrost/panfrost_devfreq.c | 14 +-------------
  drivers/gpu/drm/panfrost/panfrost_devfreq.h |  3 ---
  2 files changed, 1 insertion(+), 16 deletions(-)

drivers/gpu/drm/panfrost/panfrost_devfreq.c +1 -13

index 56b3f5935703..4d96edf1bc54 100644
@@ -3,7 +3,6 @@
 
  #include <linux/clk.h>
  #include <linux/devfreq.h>
-#include <linux/devfreq_cooling.h>
  #include <linux/platform_device.h>
  #include <linux/pm_opp.h>
 

@@ -80,6 +79,7 @@ static struct devfreq_dev_profile panfrost_devfreq_profile = {
  	.polling_ms = 50, /* ~3 frames */
  	.target = panfrost_devfreq_target,
  	.get_dev_status = panfrost_devfreq_get_dev_status,
+	.is_cooling_device = true,
  };
 
  int panfrost_devfreq_init(struct panfrost_device *pfdev)

@@ -90,7 +90,6 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
  	struct device *dev = &pfdev->pdev->dev;
  	struct devfreq *devfreq;
  	struct opp_table *opp_table;
-	struct thermal_cooling_device *cooling;
  	struct panfrost_devfreq *pfdevfreq = &pfdev->pfdevfreq;
 
  	opp_table = dev_pm_opp_set_regulators(dev, pfdev->comp->supply_names,

@@ -139,12 +138,6 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev)
  	}
  	pfdevfreq->devfreq = devfreq;
 
-	cooling = devfreq_cooling_em_register(devfreq, NULL);
-	if (IS_ERR(cooling))
-		DRM_DEV_INFO(dev, "Failed to register cooling device\n");
-	else
-		pfdevfreq->cooling = cooling;
-
  	return 0;
 
  err_fini:

@@ -156,11 +149,6 @@ void panfrost_devfreq_fini(struct panfrost_device *pfdev)
  {
  	struct panfrost_devfreq *pfdevfreq = &pfdev->pfdevfreq;
 
-	if (pfdevfreq->cooling) {
-		devfreq_cooling_unregister(pfdevfreq->cooling);
-		pfdevfreq->cooling = NULL;
-	}
-
  	if (pfdevfreq->opp_of_table_added) {
  		dev_pm_opp_of_remove_table(&pfdev->pdev->dev);
  		pfdevfreq->opp_of_table_added = false;

drivers/gpu/drm/panfrost/panfrost_devfreq.h +0 -1

index db6ea48e21f9..470f5c974703 100644
@@ -9,14 +9,11 @@
 
  struct devfreq;
  struct opp_table;
-struct thermal_cooling_device;

Currently the default behavior is to manually having the devfreq backend to register themselves as a devfreq cooling device.

Instead of adding the code in the drivers for the thermal cooling device registering, let's provide a flag in the devfreq's profile to tell the common devfreq code to register the newly created devfreq as a cooling device.

Suggested-by Chanwoo Choi <[email protected]>

Signed-off-by Daniel Lezcano <[email protected]>

---
V5:
- Changed subject prefix by: PM / devfreq
V4:
- Replaced thermal_cooling_device_unregister() by devfreq_cooling_unregister()
V3:
- Rebased on linux-pm branch without units.h
- Set the cdev to NULL in case of error
- Added description for the cdev field in the devfreq structure
V2:
- Added is_cooling_device boolean in profile structure
- Register cooling device when the is_cooling_device boolean is set
- Remove devfreq cooling device registration in the backend drivers
V1:
- Register devfreq as a cooling device unconditionnally

---
  drivers/devfreq/devfreq.c | 13 +++++++++++++
  include/linux/devfreq.h   |  8 ++++++++
  2 files changed, 21 insertions(+)

drivers/devfreq/devfreq.c +2 -0

index bf3047896e41..8a535d4d6083 100644
@@ -11,6 +11,7 @@
  #include <linux/kmod.h>
  #include <linux/sched.h>
  #include <linux/debugfs.h>
+#include <linux/devfreq_cooling.h>
  #include <linux/errno.h>
  #include <linux/err.h>
  #include <linux/init.h>

@@ -26,6 +27,7 @@
  #include <linux/hrtimer.h>
  #include <linux/of.h>
  #include <linux/pm_qos.h>
+#include <linux/thermal.h>
  #include "governor.h"
 
  #define CREATE_TRACE_POINTS

drivers/devfreq/devfreq.c +6 -0

+			devfreq->cdev = NULL;
+		}
+	}
+
  	return devfreq;
 
  err_init:

@@ -960,6 +971,8 @@ int devfreq_remove_device(struct devfreq *devfreq)
  	if (!devfreq)
  		return -EINVAL;
 
+	devfreq_cooling_unregister(devfreq->cdev);
+
  	if (devfreq->governor) {
  		devfreq->governor->event_handler(devfreq,
  						 DEVFREQ_GOV_STOP, NULL);

include/linux/devfreq.h +8 -0

index 26ea0850be9b..aba7ace11b72 100644
@@ -98,11 +98,15 @@ struct devfreq_dev_status {
   * @freq_table:		Optional list of frequencies to support statistics
   *			and freq_table must be generated in ascending order.
   * @max_state:		The size of freq_table.
+ *
+ * @is_cooling_device: A self-explanatory boolean giving the device a
+ *                     cooling effect property.
   */
  struct devfreq_dev_profile {
  	unsigned long initial_freq;
  	unsigned int polling_ms;
  	enum devfreq_timer timer;
+	bool is_cooling_device;
 
  	int (*target)(struct device *dev, unsigned long *freq, u32 flags);
  	int (*get_dev_status)(struct device *dev,

@@ -156,6 +160,7 @@ struct devfreq_stats {
   * @suspend_count:	 suspend requests counter for a device.
   * @stats:	Statistics of devfreq device behavior
   * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
+ * @cdev:	Cooling device pointer if the devfreq has cooling property
   * @nb_min:		Notifier block for DEV_PM_QOS_MIN_FREQUENCY
   * @nb_max:		Notifier block for DEV_PM_QOS_MAX_FREQUENCY
   *

@@ -198,6 +203,9 @@ struct devfreq {
 
  	struct srcu_notifier_head transition_notifier_list;
 
+	/* Pointer to the cooling device if used for thermal mitigation */
+	struct thermal_cooling_device *cdev;
+
  	struct notifier_block nb_min;
  	struct notifier_block nb_max;
  };

Currently the default behavior is to manually having the devfreq backend to register themselves as a devfreq cooling device.

Instead of adding the code in the drivers for the thermal cooling device registering, let's provide a flag in the devfreq's profile to tell the common devfreq code to register the newly created devfreq as a cooling device.

Suggested-by Chanwoo Choi <[email protected]>

Signed-off-by Daniel Lezcano <[email protected]>

---
V5:
- Changed subject prefix by: PM / devfreq
V4:
- Replaced thermal_cooling_device_unregister() by devfreq_cooling_unregister()
V3:
- Rebased on linux-pm branch without units.h
- Set the cdev to NULL in case of error
- Added description for the cdev field in the devfreq structure
V2:
- Added is_cooling_device boolean in profile structure
- Register cooling device when the is_cooling_device boolean is set
- Remove devfreq cooling device registration in the backend drivers
V1:
- Register devfreq as a cooling device unconditionnally

---
  drivers/devfreq/devfreq.c | 13 +++++++++++++
  include/linux/devfreq.h   |  8 ++++++++
  2 files changed, 21 insertions(+)

drivers/devfreq/devfreq.c +1 -0

index bf3047896e41..8a535d4d6083 100644
@@ -11,6 +11,7 @@
  #include <linux/kmod.h>
  #include <linux/sched.h>
  #include <linux/debugfs.h>
+#include <linux/devfreq_cooling.h>
  #include <linux/errno.h>
  #include <linux/err.h>
  #include <linux/init.h>

drivers/devfreq/devfreq.c +6 -0

+			devfreq->cdev = NULL;
+		}
+	}
+
  	return devfreq;
 
  err_init:

@@ -960,6 +971,8 @@ int devfreq_remove_device(struct devfreq *devfreq)
  	if (!devfreq)
  		return -EINVAL;
 
+	devfreq_cooling_unregister(devfreq->cdev);
+
  	if (devfreq->governor) {
  		devfreq->governor->event_handler(devfreq,
  						 DEVFREQ_GOV_STOP, NULL);

include/linux/devfreq.h +5 -0

index 26ea0850be9b..aba7ace11b72 100644
@@ -98,11 +98,15 @@ struct devfreq_dev_status {
   * @freq_table:		Optional list of frequencies to support statistics
   *			and freq_table must be generated in ascending order.
   * @max_state:		The size of freq_table.
+ *
+ * @is_cooling_device: A self-explanatory boolean giving the device a
+ *                     cooling effect property.
   */
  struct devfreq_dev_profile {
  	unsigned long initial_freq;
  	unsigned int polling_ms;
  	enum devfreq_timer timer;
+	bool is_cooling_device;
 
  	int (*target)(struct device *dev, unsigned long *freq, u32 flags);
  	int (*get_dev_status)(struct device *dev,

@@ -156,6 +160,7 @@ struct devfreq_stats {
   * @suspend_count:	 suspend requests counter for a device.
   * @stats:	Statistics of devfreq device behavior
   * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
+ * @cdev:	Cooling device pointer if the devfreq has cooling property
   * @nb_min:		Notifier block for DEV_PM_QOS_MIN_FREQUENCY
   * @nb_max:		Notifier block for DEV_PM_QOS_MAX_FREQUENCY
   *

Hi Daniel,

In general the approach is good. If there is a special GPU driver, which would like to provide 'struct devfreq_cooling_power *' it would leave 'is_cooling_device=false' and register manually:
devfreq_cooling_em_register(df, dfc_power);

Please find only a few minor comments below.

Quoted 11 lines · Daniel Lezcano

Currently the default behavior is to manually having the devfreq backend to register themselves as a devfreq cooling device.

Instead of adding the code in the drivers for the thermal cooling device registering, let's provide a flag in the devfreq's profile to tell the common devfreq code to register the newly created devfreq as a cooling device.

Suggested-by Chanwoo Choi <[email protected]>

Signed-off-by Daniel Lezcano <[email protected]>

---

Quoted 1 line

+    struct thermal_cooling_device *cdev;

The linux/thermal.h for 'cdev' would be needed in this header.

Quoted 5 lines

+
      struct notifier_block nb_min;
      struct notifier_block nb_max;
  };

With this small changes:

Reviewed-by Lukasz Luba <[email protected]>

Regards,
Lukasz

Quoted 22 lines · Lukasz Luba

Hi Daniel,

In general the approach is good. If there is a special GPU driver, which would like to provide 'struct devfreq_cooling_power *' it would leave 'is_cooling_device=false' and register manually:
devfreq_cooling_em_register(df, dfc_power);

Please find only a few minor comments below.

Quoted 11 lines · Daniel Lezcano

Currently the default behavior is to manually having the devfreq backend to register themselves as a devfreq cooling device.

Instead of adding the code in the drivers for the thermal cooling device registering, let's provide a flag in the devfreq's profile to tell the common devfreq code to register the newly created devfreq as a cooling device.

Suggested-by Chanwoo Choi <[email protected]>

Signed-off-by Daniel Lezcano <[email protected]>

---

[ ... ]

Quoted 3 lines

Quoted 1 line

+    struct thermal_cooling_device *cdev;

The linux/thermal.h for 'cdev' would be needed in this header.

May be just a forward declaration ?

struct thermal_cooling_device;