thermal: intel: int340x: Fix temperature selection around 0 C

Since commit 7251b9e8a007 ("thermal/intel: Fix intel_tcc_get_temp() to
support negative CPU temperature"), intel_tcc_get_temp() can report
negative temperatures.

proc_thermal_get_zone_temp() still uses *temp as the current maximum and
as an implicit "no reading yet" marker. However, this breaks when a CPU
reports 0 C, because a subsequent negative reading can overwrite it.

Use bool temp_valid to track whether a valid temperature has been read.
Initialize *temp with the first valid reading and only update it with
warmer readings.

Fixes: 7251b9e8a007 ("thermal/intel: Fix intel_tcc_get_temp() to support negative CPU temperature")
Cc: 6.3+ <stable@vger.kernel.org> # 6.3+
Signed-off-by: Thorsten Blum <blum@kernel.org>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://patch.msgid.link/20260826153144.299746-3-blum@kernel.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 7 insertions, 3 deletions

diff --git a/drivers/thermal/intel/int340x_thermal/processor_thermal_device.c b/drivers/thermal/intel/int340x_thermal/processor_thermal_device.c
index 0a007a6413df..850bfe7c1ede 100644
--- a/drivers/thermal/intel/int340x_thermal/processor_thermal_device.c
+++ b/drivers/thermal/intel/int340x_thermal/processor_thermal_device.c
@@ -179,17 +179,21 @@ static int proc_thermal_get_zone_temp(struct thermal_zone_device *zone,
 {
 	int cpu;
 	int curr_temp, ret;
-
-	*temp = 0;
+	bool temp_valid = false;
 
 	for_each_online_cpu(cpu) {
 		ret = intel_tcc_get_temp(cpu, &curr_temp, false);
 		if (ret < 0)
 			return ret;
-		if (!*temp || curr_temp > *temp)
+		if (!temp_valid || curr_temp > *temp) {
 			*temp = curr_temp;
+			temp_valid = true;
+		}
 	}
 
+	if (!temp_valid)
+		return -ENODATA;
+
 	*temp *= 1000;
 
 	return 0;