mlxsw: core: Modify thermal zone definition

Modify thermal zone trip points setting for better alignment with system
thermal requirement.

Add hysteresis thresholds for thermal trips in order to avoid throttling
around thermal trip point. If hysteresis temperature is not considered,
PWM can have side effect of flip up/down on thermal trip point boundary.
Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/core_thermal.c

@@ -15,6 +15,7 @@
 #define MLXSW_THERMAL_POLL_INT	1000	/* ms */
 #define MLXSW_THERMAL_SLOW_POLL_INT	20000	/* ms */
 #define MLXSW_THERMAL_MAX_TEMP	110000	/* 110C */
+#define MLXSW_THERMAL_HYSTERESIS_TEMP	5000	/* 5C */
 #define MLXSW_THERMAL_MAX_STATE	10
 #define MLXSW_THERMAL_MAX_DUTY	255
 /* Minimum and maximum fan allowed speed in percent: from 20% to 100%. Values
@@ -30,6 +31,7 @@
 struct mlxsw_thermal_trip {
 	int	type;
 	int	temp;
+	int	hyst;
 	int	min_state;
 	int	max_state;
 };
@@ -38,25 +40,22 @@ static const struct mlxsw_thermal_trip default_thermal_trips[] = {
 	{	/* In range - 0-40% PWM */
 		.type		= THERMAL_TRIP_ACTIVE,
 		.temp		= 75000,
+		.hyst		= MLXSW_THERMAL_HYSTERESIS_TEMP,
 		.min_state	= 0,
 		.max_state	= (4 * MLXSW_THERMAL_MAX_STATE) / 10,
 	},
-	{	/* High - 40-100% PWM */
+	{
+		/* In range - 40-100% PWM */
 		.type		= THERMAL_TRIP_ACTIVE,
 		.temp		= 80000,
+		.hyst		= MLXSW_THERMAL_HYSTERESIS_TEMP,
 		.min_state	= (4 * MLXSW_THERMAL_MAX_STATE) / 10,
 		.max_state	= MLXSW_THERMAL_MAX_STATE,
 	},
-	{
-		/* Very high - 100% PWM */
-		.type		= THERMAL_TRIP_ACTIVE,
-		.temp		= 85000,
-		.min_state	= MLXSW_THERMAL_MAX_STATE,
-		.max_state	= MLXSW_THERMAL_MAX_STATE,
-	},
 	{	/* Warning */
 		.type		= THERMAL_TRIP_HOT,
-		.temp		= 105000,
+		.temp		= 85000,
+		.hyst		= MLXSW_THERMAL_HYSTERESIS_TEMP,
 		.min_state	= MLXSW_THERMAL_MAX_STATE,
 		.max_state	= MLXSW_THERMAL_MAX_STATE,
 	},
@@ -246,6 +245,24 @@ static int mlxsw_thermal_set_trip_temp(struct thermal_zone_device *tzdev,
 	return 0;
 }
 
+static int mlxsw_thermal_get_trip_hyst(struct thermal_zone_device *tzdev,
+				       int trip, int *p_hyst)
+{
+	struct mlxsw_thermal *thermal = tzdev->devdata;
+
+	*p_hyst = thermal->trips[trip].hyst;
+	return 0;
+}
+
+static int mlxsw_thermal_set_trip_hyst(struct thermal_zone_device *tzdev,
+				       int trip, int hyst)
+{
+	struct mlxsw_thermal *thermal = tzdev->devdata;
+
+	thermal->trips[trip].hyst = hyst;
+	return 0;
+}
+
 static struct thermal_zone_device_ops mlxsw_thermal_ops = {
 	.bind = mlxsw_thermal_bind,
 	.unbind = mlxsw_thermal_unbind,
@@ -255,6 +272,8 @@ static struct thermal_zone_device_ops mlxsw_thermal_ops = {
 	.get_trip_type	= mlxsw_thermal_get_trip_type,
 	.get_trip_temp	= mlxsw_thermal_get_trip_temp,
 	.set_trip_temp	= mlxsw_thermal_set_trip_temp,
+	.get_trip_hyst	= mlxsw_thermal_get_trip_hyst,
+	.set_trip_hyst	= mlxsw_thermal_set_trip_hyst,
 };
 
 static int mlxsw_thermal_get_max_state(struct thermal_cooling_device *cdev,