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From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Linux PM <linux-pm@vger.kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
 "Rafael J. Wysocki" <rafael@kernel.org>, Lukasz Luba <lukasz.luba@arm.com>,
 Daniel Lezcano <daniel.lezcano@linaro.org>
Subject:
 [PATCH v1 2/3] thermal/debugfs: Pass cooling device state to
 thermal_debug_cdev_add()
Date: Tue, 23 Apr 2024 20:00:57 +0200
Message-ID: <2181352.irdbgypaU6@kreacher>
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From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

If cdev_dt_seq_show() runs before the first state transition of a cooling
device, it will not print any state residency information for it, even
though it might be reasonably expected to print residency information for
the initial state of the cooling device.

For this reason, rearrange the code to get the initial state of a cooling
device at the registration time and pass it to thermal_debug_cdev_add(),
so that the latter can create a duration record for that state which will
allow cdev_dt_seq_show() to print its residency information.

Fixes: 755113d76786 ("thermal/debugfs: Add thermal cooling device debugfs information")
Reported-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/thermal/thermal_core.c    |    9 +++++++--
 drivers/thermal/thermal_debugfs.c |   12 ++++++++++--
 drivers/thermal/thermal_debugfs.h |    4 ++--
 3 files changed, 19 insertions(+), 6 deletions(-)

Index: linux-pm/drivers/thermal/thermal_core.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_core.c
+++ linux-pm/drivers/thermal/thermal_core.c
@@ -928,6 +928,7 @@ __thermal_cooling_device_register(struct
 {
 	struct thermal_cooling_device *cdev;
 	struct thermal_zone_device *pos = NULL;
+	unsigned long current_state;
 	int id, ret;
 
 	if (!ops || !ops->get_max_state || !ops->get_cur_state ||
@@ -965,6 +966,10 @@ __thermal_cooling_device_register(struct
 	if (ret)
 		goto out_cdev_type;
 
+	ret = cdev->ops->get_cur_state(cdev, &current_state);
+	if (ret)
+		goto out_cdev_type;
+
 	thermal_cooling_device_setup_sysfs(cdev);
 
 	ret = dev_set_name(&cdev->device, "cooling_device%d", cdev->id);
@@ -978,6 +983,8 @@ __thermal_cooling_device_register(struct
 		return ERR_PTR(ret);
 	}
 
+	thermal_debug_cdev_add(cdev, current_state);
+
 	/* Add 'this' new cdev to the global cdev list */
 	mutex_lock(&thermal_list_lock);
 
@@ -993,8 +1000,6 @@ __thermal_cooling_device_register(struct
 
 	mutex_unlock(&thermal_list_lock);
 
-	thermal_debug_cdev_add(cdev);
-
 	return cdev;
 
 out_cooling_dev:
Index: linux-pm/drivers/thermal/thermal_debugfs.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_debugfs.c
+++ linux-pm/drivers/thermal/thermal_debugfs.c
@@ -466,8 +466,9 @@ void thermal_debug_cdev_state_update(con
  * Allocates a cooling device object for debug, initializes the
  * statistics and create the entries in sysfs.
  * @cdev: a pointer to a cooling device
+ * @state: current state of the cooling device
  */
-void thermal_debug_cdev_add(struct thermal_cooling_device *cdev)
+void thermal_debug_cdev_add(struct thermal_cooling_device *cdev, int state)
 {
 	struct thermal_debugfs *thermal_dbg;
 	struct cdev_debugfs *cdev_dbg;
@@ -484,9 +485,16 @@ void thermal_debug_cdev_add(struct therm
 		INIT_LIST_HEAD(&cdev_dbg->durations[i]);
 	}
 
-	cdev_dbg->current_state = 0;
+	cdev_dbg->current_state = state;
 	cdev_dbg->timestamp = ktime_get();
 
+	/*
+	 * Create a record for the initial cooling device state, so its
+	 * duration will be printed by cdev_dt_seq_show() as expected if it
+	 * runs before the first state transition.
+	 */
+	thermal_debugfs_cdev_record_get(thermal_dbg, cdev_dbg->durations, state);
+
 	debugfs_create_file("trans_table", 0400, thermal_dbg->d_top,
 			    thermal_dbg, &tt_fops);
 
Index: linux-pm/drivers/thermal/thermal_debugfs.h
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_debugfs.h
+++ linux-pm/drivers/thermal/thermal_debugfs.h
@@ -2,7 +2,7 @@
 
 #ifdef CONFIG_THERMAL_DEBUGFS
 void thermal_debug_init(void);
-void thermal_debug_cdev_add(struct thermal_cooling_device *cdev);
+void thermal_debug_cdev_add(struct thermal_cooling_device *cdev, int state);
 void thermal_debug_cdev_remove(struct thermal_cooling_device *cdev);
 void thermal_debug_cdev_state_update(const struct thermal_cooling_device *cdev, int state);
 void thermal_debug_tz_add(struct thermal_zone_device *tz);
@@ -14,7 +14,7 @@ void thermal_debug_tz_trip_down(struct t
 void thermal_debug_update_stats(struct thermal_zone_device *tz);
 #else
 static inline void thermal_debug_init(void) {}
-static inline void thermal_debug_cdev_add(struct thermal_cooling_device *cdev) {}
+static inline void thermal_debug_cdev_add(struct thermal_cooling_device *cdev, int state) {}
 static inline void thermal_debug_cdev_remove(struct thermal_cooling_device *cdev) {}
 static inline void thermal_debug_cdev_state_update(const struct thermal_cooling_device *cdev,
 						   int state) {}