thermal/drivers/mediatek/lvts: Disable Stage 3 thermal threshold

The Stage 3 thermal threshold is currently configured during
the controller initialization to 105 Celsius. From the kernel
perspective, this configuration is harmful because:
* The stage 3 interrupt that gets triggered when the threshold is
  crossed is not handled in any way by the IRQ handler, it just gets
  cleared. Besides, the temperature used for stage 3 comes from the
  sensors, and the critical thermal trip points described in the
  Devicetree will already cause a shutdown when crossed (at a lower
  temperature, of 100 Celsius, for all SoCs currently using this
  driver).
* The only effect of crossing the stage 3 threshold that has been
  observed is that it causes the machine to no longer be able to enter
  suspend. Even if that was a result of a momentary glitch in the
  temperature reading of a sensor (as has been observed on the
  MT8192-based Chromebooks).

For those reasons, disable the Stage 3 thermal threshold configuration.

Cc: [email protected]
Reported-by: Hsin-Te Yuan <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Fixes: f5f633b ("thermal/drivers/mediatek: Add the Low Voltage Thermal Sensor driver")
Reviewed-by: AngeloGioacchino Del Regno <[email protected]>
Signed-off-by: Nícolas F. R. A. Prado <[email protected]>
Link: https://lore.kernel.org/r/20250113-mt8192-lvts-filtered-suspend-fix-v2-2-07a25200c7c6@collabora.com
Signed-off-by: Daniel Lezcano <[email protected]>

Author: nfraprado

drivers/thermal/mediatek/lvts_thermal.c

@@ -65,7 +65,7 @@
 #define LVTS_HW_FILTER				0x0
 #define LVTS_TSSEL_CONF				0x13121110
 #define LVTS_CALSCALE_CONF			0x300
-#define LVTS_MONINT_CONF			0x8300318C
+#define LVTS_MONINT_CONF			0x0300318C
 
 #define LVTS_MONINT_OFFSET_SENSOR0		0xC
 #define LVTS_MONINT_OFFSET_SENSOR1		0x180
@@ -91,8 +91,6 @@
 #define LVTS_MSR_READ_TIMEOUT_US	400
 #define LVTS_MSR_READ_WAIT_US		(LVTS_MSR_READ_TIMEOUT_US / 2)
 
-#define LVTS_HW_TSHUT_TEMP		105000
-
 #define LVTS_MINIMUM_THRESHOLD		20000
 
 static int golden_temp = LVTS_GOLDEN_TEMP_DEFAULT;
@@ -145,7 +143,6 @@ struct lvts_ctrl {
 	struct lvts_sensor sensors[LVTS_SENSOR_MAX];
 	const struct lvts_data *lvts_data;
 	u32 calibration[LVTS_SENSOR_MAX];
-	u32 hw_tshut_raw_temp;
 	u8 valid_sensor_mask;
 	int mode;
 	void __iomem *base;
@@ -837,14 +834,6 @@ static int lvts_ctrl_init(struct device *dev, struct lvts_domain *lvts_td,
 		 */
 		lvts_ctrl[i].mode = lvts_data->lvts_ctrl[i].mode;
 
-		/*
-		 * The temperature to raw temperature must be done
-		 * after initializing the calibration.
-		 */
-		lvts_ctrl[i].hw_tshut_raw_temp =
-			lvts_temp_to_raw(LVTS_HW_TSHUT_TEMP,
-					 lvts_data->temp_factor);
-
 		lvts_ctrl[i].low_thresh = INT_MIN;
 		lvts_ctrl[i].high_thresh = INT_MIN;
 	}
@@ -919,7 +908,6 @@ static int lvts_irq_init(struct lvts_ctrl *lvts_ctrl)
 	 *         10 : Selected sensor with bits 19-18
 	 *         11 : Reserved
 	 */
-	writel(BIT(16), LVTS_PROTCTL(lvts_ctrl->base));
 
 	/*
 	 * LVTS_PROTTA : Stage 1 temperature threshold
@@ -932,8 +920,8 @@ static int lvts_irq_init(struct lvts_ctrl *lvts_ctrl)
 	 *
 	 * writel(0x0, LVTS_PROTTA(lvts_ctrl->base));
 	 * writel(0x0, LVTS_PROTTB(lvts_ctrl->base));
+	 * writel(0x0, LVTS_PROTTC(lvts_ctrl->base));
 	 */
-	writel(lvts_ctrl->hw_tshut_raw_temp, LVTS_PROTTC(lvts_ctrl->base));
 
 	/*
 	 * LVTS_MONINT : Interrupt configuration register