thermal: ACPI: Invalidate trip points with temperature of 0 or below

It is reported that commit 9502108 ("thermal: core: Drop
trips_disabled bitmask") causes the maximum frequency of CPUs to drop
further down with every system sleep-wake cycle on Intel Core i7-4710HQ.

This turns out to be due to a trip point whose temperature is equal to 0
degrees Celsius which is acted on every time the system wakes from sleep.

Before commit 9502108 this trip point would be disabled wia the
trips_disabled bitmask, but now it is treated as a valid one.

Since ACPI thermal control is generally about protection against
overheating, trip points with temperature of 0 centigrade or below are
not particularly useful there, so initialize them all as invalid which
fixes the problem at hand.

Fixes: 9502108 ("thermal: core: Drop trips_disabled bitmask")
Closes: https://lore.kernel.org/linux-pm/[email protected]
Reported-by: Tibor Billes <[email protected]>
Tested-by: Tibor Billes <[email protected]>
Cc: 6.7+ <[email protected]> # 6.7+
Signed-off-by: Rafael J. Wysocki <[email protected]>

Author: rafaeljw

drivers/acpi/thermal.c

@@ -168,11 +168,17 @@ static int acpi_thermal_get_polling_frequency(struct acpi_thermal *tz)
 
 static int acpi_thermal_temp(struct acpi_thermal *tz, int temp_deci_k)
 {
+	int temp;
+
 	if (temp_deci_k == THERMAL_TEMP_INVALID)
 		return THERMAL_TEMP_INVALID;
 
-	return deci_kelvin_to_millicelsius_with_offset(temp_deci_k,
+	temp = deci_kelvin_to_millicelsius_with_offset(temp_deci_k,
 						       tz->kelvin_offset);
+	if (temp <= 0)
+		return THERMAL_TEMP_INVALID;
+
+	return temp;
 }
 
 static bool acpi_thermal_trip_valid(struct acpi_thermal_trip *acpi_trip)