thermal: step_wise: fix: Prevent from binary overflow when trend is dropping

It turns out that some boards can have instance->lower greater than 0 and
when thermal trend is dropping it results with next_target equal to -1.

Since the next_target is defined as unsigned long it is interpreted as
0xFFFFFFFF and larger than instance->upper.
As a result the next_target is set to instance->upper which ramps up to
maximal cooling device target when the temperature is steadily decreasing.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/thermal/step_wise.c b/drivers/thermal/step_wise.c
index f251521baaa2..6705a0d746b3 100644
--- a/drivers/thermal/step_wise.c
+++ b/drivers/thermal/step_wise.c
@@ -76,7 +76,7 @@ static unsigned long get_target_state(struct thermal_instance *instance,
                         next_target = instance->upper;
                 break;
         case THERMAL_TREND_DROPPING:
-                if (cur_state == instance->lower) {
+                if (cur_state <= instance->lower) {
                         if (!throttle)
                                 next_target = THERMAL_NO_TARGET;
                 } else {