linux-kernel - [PATCH] of-thermal: Disable polling when interrupt property is found in DT

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Date:   Wed, 16 Oct 2019 04:43:16 +0530
From:   Amit Kucheria <amit.kucheria@...aro.org>
To:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        swboyd@...omium.org, Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     linux-pm@...r.kernel.org
Subject: [PATCH] of-thermal: Disable polling when interrupt property is found in DT

Currently, in order to enable interrupt-only mode, one must set
polling-delay-passive and polling-delay properties in the DT to 0,
otherwise the thermal framework will continue to setup a periodic timers
to monitor the thermal zones.

Change the behaviour, so that on DT-based systems, we no longer have to
set the properties to zero if we find an 'interrupt' property in the
sensor.

Following data shows the number of times
thermal_zone_device_set_polling() is invoked with and without this
patch. So the patch achieves the same behaviour as setting the delay
properties to 0.

Current behaviour (without setting delay properties to 0):
  FUNC                              COUNT
  thermal_zone_device_update          302
  thermal_zone_device_set_pollin     7911

Current behaviour (with delay properties set to 0):
  FUNC                              COUNT
  thermal_zone_device_update            3
  thermal_zone_device_set_pollin        6

With this patch (without setting delay properties to 0):
  FUNC                              COUNT
  thermal_zone_device_update            3
  thermal_zone_device_set_pollin        6

Suggested-by: Stephen Boyd <swboyd@...omium.org>
Signed-off-by: Amit Kucheria <amit.kucheria@...aro.org>
---
 drivers/thermal/of-thermal.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/thermal/of-thermal.c b/drivers/thermal/of-thermal.c
index dc5093be553e..79ad587462b1 100644
--- a/drivers/thermal/of-thermal.c
+++ b/drivers/thermal/of-thermal.c
@@ -412,7 +412,8 @@ static struct thermal_zone_device_ops of_thermal_ops = {
 static struct thermal_zone_device *
 thermal_zone_of_add_sensor(struct device_node *zone,
 			   struct device_node *sensor, void *data,
-			   const struct thermal_zone_of_device_ops *ops)
+			   const struct thermal_zone_of_device_ops *ops,
+			   bool force_interrupts)
 {
 	struct thermal_zone_device *tzd;
 	struct __thermal_zone *tz;
@@ -433,6 +434,11 @@ thermal_zone_of_add_sensor(struct device_node *zone,
 	tzd->ops->get_temp = of_thermal_get_temp;
 	tzd->ops->get_trend = of_thermal_get_trend;
 
+	if (force_interrupts) {
+		tz->passive_delay = 0;
+		tz->polling_delay = 0;
+	}
+
 	/*
 	 * The thermal zone core will calculate the window if they have set the
 	 * optional set_trips pointer.
@@ -486,6 +492,7 @@ thermal_zone_of_sensor_register(struct device *dev, int sensor_id, void *data,
 {
 	struct device_node *np, *child, *sensor_np;
 	struct thermal_zone_device *tzd = ERR_PTR(-ENODEV);
+	bool force_interrupts = false;
 
 	np = of_find_node_by_name(NULL, "thermal-zones");
 	if (!np)
@@ -498,6 +505,9 @@ thermal_zone_of_sensor_register(struct device *dev, int sensor_id, void *data,
 
 	sensor_np = of_node_get(dev->of_node);
 
+	if (of_find_property(sensor_np, "interrupts", NULL))
+		force_interrupts = true;
+
 	for_each_available_child_of_node(np, child) {
 		struct of_phandle_args sensor_specs;
 		int ret, id;
@@ -520,7 +530,8 @@ thermal_zone_of_sensor_register(struct device *dev, int sensor_id, void *data,
 
 		if (sensor_specs.np == sensor_np && id == sensor_id) {
 			tzd = thermal_zone_of_add_sensor(child, sensor_np,
-							 data, ops);
+							 data, ops,
+							 force_interrupts);
 			if (!IS_ERR(tzd))
 				tzd->ops->set_mode(tzd, THERMAL_DEVICE_ENABLED);
 
-- 
2.17.1