linux-kernel - [PATCH v2 1/5] thermal/drivers/mediatek/lvts: Disable monitor mode during suspend

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Message-Id: <20241209-mt8192-lvts-filtered-suspend-fix-v2-1-5b046a99baa9@collabora.com>
Date: Mon, 09 Dec 2024 14:00:02 -0300
From: Nícolas F. R. A. Prado <nfraprado@...labora.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>, 
 Daniel Lezcano <daniel.lezcano@...aro.org>, Zhang Rui <rui.zhang@...el.com>, 
 Lukasz Luba <lukasz.luba@....com>, 
 Matthias Brugger <matthias.bgg@...il.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 Alexandre Mergnat <amergnat@...libre.com>, 
 Balsam CHIHI <bchihi@...libre.com>
Cc: kernel@...labora.com, linux-pm@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 linux-mediatek@...ts.infradead.org, Hsin-Te Yuan <yuanhsinte@...omium.org>, 
 Chen-Yu Tsai <wenst@...omium.org>, 
 Bernhard Rosenkränzer <bero@...libre.com>, 
 "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>, 
 Nícolas F. R. A. Prado <nfraprado@...labora.com>, 
 stable@...r.kernel.org
Subject: [PATCH v2 1/5] thermal/drivers/mediatek/lvts: Disable monitor mode
 during suspend

When configured in filtered mode, the LVTS thermal controller will
monitor the temperature from the sensors and trigger an interrupt once a
thermal threshold is crossed.

Currently this is true even during suspend and resume. The problem with
that is that when enabling the internal clock of the LVTS controller in
lvts_ctrl_set_enable() during resume, the temperature reading can glitch
and appear much higher than the real one, resulting in a spurious
interrupt getting generated.

Disable the temperature monitoring and give some time for the signals to
stabilize during suspend in order to prevent such spurious interrupts.

Cc: stable@...r.kernel.org
Reported-by: Hsin-Te Yuan <yuanhsinte@...omium.org>
Closes: https://lore.kernel.org/all/20241108-lvts-v1-1-eee339c6ca20@chromium.org/
Fixes: 8137bb90600d ("thermal/drivers/mediatek/lvts_thermal: Add suspend and resume")
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>
---
 drivers/thermal/mediatek/lvts_thermal.c | 36 +++++++++++++++++++++++++++++++--
 1 file changed, 34 insertions(+), 2 deletions(-)

diff --git a/drivers/thermal/mediatek/lvts_thermal.c b/drivers/thermal/mediatek/lvts_thermal.c
index 07f7f3b7a2fb569cfc300dc2126ea426e161adff..a1a438ebad33c1fff8ca9781e12ef9e278eef785 100644
--- a/drivers/thermal/mediatek/lvts_thermal.c
+++ b/drivers/thermal/mediatek/lvts_thermal.c
@@ -860,6 +860,32 @@ static int lvts_ctrl_init(struct device *dev, struct lvts_domain *lvts_td,
 	return 0;
 }

+static void lvts_ctrl_monitor_enable(struct device *dev, struct lvts_ctrl *lvts_ctrl, bool enable)
+{
+	/*
+	 * Bitmaps to enable each sensor on filtered mode in the MONCTL0
+	 * register.
+	 */
+	static const u8 sensor_filt_bitmap[] = { BIT(0), BIT(1), BIT(2), BIT(3) };
+	u32 sensor_map = 0;
+	int i;
+
+	if (lvts_ctrl->mode != LVTS_MSR_FILTERED_MODE)
+		return;
+
+	if (enable) {
+		lvts_for_each_valid_sensor(i, lvts_ctrl)
+			sensor_map |= sensor_filt_bitmap[i];
+	}
+
+	/*
+	 * Bits:
+	 *      9: Single point access flow
+	 *    0-3: Enable sensing point 0-3
+	 */
+	writel(sensor_map | BIT(9), LVTS_MONCTL0(lvts_ctrl->base));
+}
+
 /*
  * At this point the configuration register is the only place in the
  * driver where we write multiple values. Per hardware constraint,
@@ -1381,8 +1407,11 @@ static int lvts_suspend(struct device *dev)

 	lvts_td = dev_get_drvdata(dev);

-	for (i = 0; i < lvts_td->num_lvts_ctrl; i++)
+	for (i = 0; i < lvts_td->num_lvts_ctrl; i++) {
+		lvts_ctrl_monitor_enable(dev, &lvts_td->lvts_ctrl[i], false);
+		usleep_range(100, 200);
 		lvts_ctrl_set_enable(&lvts_td->lvts_ctrl[i], false);
+	}

 	clk_disable_unprepare(lvts_td->clk);

@@ -1400,8 +1429,11 @@ static int lvts_resume(struct device *dev)
 	if (ret)
 		return ret;

-	for (i = 0; i < lvts_td->num_lvts_ctrl; i++)
+	for (i = 0; i < lvts_td->num_lvts_ctrl; i++) {
 		lvts_ctrl_set_enable(&lvts_td->lvts_ctrl[i], true);
+		usleep_range(100, 200);
+		lvts_ctrl_monitor_enable(dev, &lvts_td->lvts_ctrl[i], true);
+	}

 	return 0;
 }

-- 
2.47.0