[PATCH v2 3/5] thermal/drivers/mediatek/lvts: Disable low offset IRQ for minimum threshold

[Nícolas F. R. A. Prado]

In order to get working interrupts, a low offset value needs to be
configured. The minimum value for it is 20 Celsius, which is what is
configured when there's no lower thermal trip (ie the thermal core
passes -INT_MAX as low trip temperature). However, when the temperature
gets that low and fluctuates around that value it causes an interrupt
storm.

Prevent that interrupt storm by not enabling the low offset interrupt if
the low threshold is the minimum one.

Cc: stable at vger.kernel.org
Fixes: 77354eaef821 ("thermal/drivers/mediatek/lvts_thermal: Don't leave threshold zeroed")
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno at collabora.com>
Signed-off-by: Nícolas F. R. A. Prado <nfraprado at collabora.com>
---
 drivers/thermal/mediatek/lvts_thermal.c | 48 ++++++++++++++++++++++++---------
 1 file changed, 35 insertions(+), 13 deletions(-)

diff --git a/drivers/thermal/mediatek/lvts_thermal.c b/drivers/thermal/mediatek/lvts_thermal.c
index 0aaa44b734ca43e6abfd97b2ca4ce34dc6f15826..04bfbfe93a71ee9e3428bfd7f8bd359fe9446e88 100644
--- a/drivers/thermal/mediatek/lvts_thermal.c
+++ b/drivers/thermal/mediatek/lvts_thermal.c
@@ -67,10 +67,14 @@
 #define LVTS_CALSCALE_CONF			0x300
 #define LVTS_MONINT_CONF			0x0300318C
 
-#define LVTS_MONINT_OFFSET_SENSOR0		0xC
-#define LVTS_MONINT_OFFSET_SENSOR1		0x180
-#define LVTS_MONINT_OFFSET_SENSOR2		0x3000
-#define LVTS_MONINT_OFFSET_SENSOR3		0x3000000
+#define LVTS_MONINT_OFFSET_HIGH_INTEN_SENSOR0		BIT(3)
+#define LVTS_MONINT_OFFSET_HIGH_INTEN_SENSOR1		BIT(8)
+#define LVTS_MONINT_OFFSET_HIGH_INTEN_SENSOR2		BIT(13)
+#define LVTS_MONINT_OFFSET_HIGH_INTEN_SENSOR3		BIT(25)
+#define LVTS_MONINT_OFFSET_LOW_INTEN_SENSOR0		BIT(2)
+#define LVTS_MONINT_OFFSET_LOW_INTEN_SENSOR1		BIT(7)
+#define LVTS_MONINT_OFFSET_LOW_INTEN_SENSOR2		BIT(12)
+#define LVTS_MONINT_OFFSET_LOW_INTEN_SENSOR3		BIT(24)
 
 #define LVTS_INT_SENSOR0			0x0009001F
 #define LVTS_INT_SENSOR1			0x001203E0
@@ -326,11 +330,17 @@ static int lvts_get_temp(struct thermal_zone_device *tz, int *temp)
 
 static void lvts_update_irq_mask(struct lvts_ctrl *lvts_ctrl)
 {
-	static const u32 masks[] = {
-		LVTS_MONINT_OFFSET_SENSOR0,
-		LVTS_MONINT_OFFSET_SENSOR1,
-		LVTS_MONINT_OFFSET_SENSOR2,
-		LVTS_MONINT_OFFSET_SENSOR3,
+	static const u32 high_offset_inten_masks[] = {
+		LVTS_MONINT_OFFSET_HIGH_INTEN_SENSOR0,
+		LVTS_MONINT_OFFSET_HIGH_INTEN_SENSOR1,
+		LVTS_MONINT_OFFSET_HIGH_INTEN_SENSOR2,
+		LVTS_MONINT_OFFSET_HIGH_INTEN_SENSOR3,
+	};
+	static const u32 low_offset_inten_masks[] = {
+		LVTS_MONINT_OFFSET_LOW_INTEN_SENSOR0,
+		LVTS_MONINT_OFFSET_LOW_INTEN_SENSOR1,
+		LVTS_MONINT_OFFSET_LOW_INTEN_SENSOR2,
+		LVTS_MONINT_OFFSET_LOW_INTEN_SENSOR3,
 	};
 	u32 value = 0;
 	int i;
@@ -339,10 +349,22 @@ static void lvts_update_irq_mask(struct lvts_ctrl *lvts_ctrl)
 
 	for (i = 0; i < ARRAY_SIZE(masks); i++) {
 		if (lvts_ctrl->sensors[i].high_thresh == lvts_ctrl->high_thresh
-		    && lvts_ctrl->sensors[i].low_thresh == lvts_ctrl->low_thresh)
-			value |= masks[i];
-		else
-			value &= ~masks[i];
+		    && lvts_ctrl->sensors[i].low_thresh == lvts_ctrl->low_thresh) {
+			/*
+			 * The minimum threshold needs to be configured in the
+			 * OFFSETL register to get working interrupts, but we
+			 * don't actually want to generate interrupts when
+			 * crossing it.
+			 */
+			if (lvts_ctrl->low_thresh == -INT_MAX) {
+				value &= ~low_offset_inten_masks[i];
+				value |= high_offset_inten_masks[i];
+			} else {
+				value |= low_offset_inten_masks[i] | high_offset_inten_masks[i];
+			}
+		} else {
+			value &= ~(low_offset_inten_masks[i] | high_offset_inten_masks[i]);
+		}
 	}
 
 	writel(value, LVTS_MONINT(lvts_ctrl->base));

-- 
2.47.0