[PATCH v2 5/6] thermal/drivers/mediatek/lvts_thermal: Don't leave threshold zeroed

[Nícolas F. R. A. Prado]

The thermal framework might leave the low threshold unset if there
aren't any lower trip points. This leaves the register zeroed, which
translates to a very high temperature for the low threshold. The
interrupt for this threshold is then immediately triggered, and the
state machine gets stuck, preventing any other temperature monitoring
interrupts to ever trigger.

(The same happens by not setting the Cold or Hot to Normal thresholds
when using those)

Set the unused threshold to a valid low value. This value was chosen so
that for any valid golden temperature read from the efuse, when the
value is converted to raw and back again to milliCelsius, the result
doesn't underflow.

Fixes: f5f633b18234 ("thermal/drivers/mediatek: Add the Low Voltage Thermal Sensor driver")
Signed-off-by: Nícolas F. R. A. Prado <nfraprado at collabora.com>

---

Changes in v2:
- Added this commit

 drivers/thermal/mediatek/lvts_thermal.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/thermal/mediatek/lvts_thermal.c b/drivers/thermal/mediatek/lvts_thermal.c
index efd1e938e1c2..951a4cb75ef6 100644
--- a/drivers/thermal/mediatek/lvts_thermal.c
+++ b/drivers/thermal/mediatek/lvts_thermal.c
@@ -82,6 +82,8 @@
 #define LVTS_HW_SHUTDOWN_MT8195		105000
 #define LVTS_HW_SHUTDOWN_MT8192		105000
 
+#define LVTS_MINIUM_THRESHOLD		20000
+
 static int golden_temp = LVTS_GOLDEN_TEMP_DEFAULT;
 static int coeff_b = LVTS_COEFF_B;
 
@@ -309,6 +311,11 @@ static int lvts_set_trips(struct thermal_zone_device *tz, int low, int high)
 		pr_debug("%s: Setting low limit temperature interrupt: %d\n",
 			 thermal_zone_device_type(tz), low);
 		writel(raw_low, LVTS_OFFSETL(base));
+	} else {
+		pr_debug("%s: Setting low limit temperature to minimum\n",
+			 thermal_zone_device_type(tz));
+		raw_low = lvts_temp_to_raw(LVTS_MINIUM_THRESHOLD);
+		writel(raw_low, LVTS_OFFSETL(base));
 	}
 
 	/*
-- 
2.40.1