[PATCH 1/3] thermal: step_wise: fix: Prevent from binary overflow when trend is dropping

Lukasz Majewski
2014-09-24T08:27:50Z

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>
---
drivers/thermal/step_wise.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/thermal/step_wise.c b/drivers/thermal/step_wise.c
index 3b54c2c..fdd1f52 100644
--- a/drivers/thermal/step_wise.c
+++ b/drivers/thermal/step_wise.c
@@ -77,7 +77,7 @@ 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 {
--
2.0.0.rc2