linux-kernel - [PATCH v2 2/7] mfd: max77686: Do not enforce (incorrect) interrupt trigger type

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Message-Id: <20210526172036.183223-3-krzysztof.kozlowski@canonical.com>
Date:   Wed, 26 May 2021 13:20:31 -0400
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
To:     Chanwoo Choi <cw00.choi@...sung.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Sebastian Reichel <sre@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org, linux-rtc@...r.kernel.org
Cc:     Krzysztof Kozlowski <krzk@...nel.org>,
        Rob Herring <robh@...nel.org>
Subject: [PATCH v2 2/7] mfd: max77686: Do not enforce (incorrect) interrupt trigger type

From: Krzysztof Kozlowski <krzk@...nel.org>

Interrupt line can be configured on different hardware in different way,
even inverted.  Therefore driver should not enforce specific trigger
type - edge falling - but instead rely on Devicetree to configure it.

The Maxim 77686 datasheet describes the interrupt line as active low
with a requirement of acknowledge from the CPU therefore the edge
falling is not correct.

The interrupt line is shared between PMIC and RTC driver, so using level
sensitive interrupt is here especially important to avoid races.  With
an edge configuration in case if first PMIC signals interrupt followed
shortly after by the RTC, the interrupt might not be yet cleared/acked
thus the second one would not be noticed.

Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>
Acked-by: Rob Herring <robh@...nel.org>

---

Changes since v1:
1. Add ack.
---
 Documentation/devicetree/bindings/clock/maxim,max77686.txt | 4 ++--
 Documentation/devicetree/bindings/mfd/max77686.txt         | 2 +-
 Documentation/devicetree/bindings/regulator/max77686.txt   | 2 +-
 drivers/mfd/max77686.c                                     | 3 +--
 4 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/clock/maxim,max77686.txt b/Documentation/devicetree/bindings/clock/maxim,max77686.txt
index 3472b461ca93..c10849efb444 100644
--- a/Documentation/devicetree/bindings/clock/maxim,max77686.txt
+++ b/Documentation/devicetree/bindings/clock/maxim,max77686.txt
@@ -49,7 +49,7 @@ Example:
 		max77686: max77686@9 {
 			compatible = "maxim,max77686";
 			interrupt-parent = <&wakeup_eint>;
-			interrupts = <26 0>;
+			interrupts = <26 IRQ_TYPE_LEVEL_LOW>;
 			reg = <0x09>;
 			#clock-cells = <1>;
 
@@ -74,7 +74,7 @@ Example:
 		max77802: max77802@9 {
 			compatible = "maxim,max77802";
 			interrupt-parent = <&wakeup_eint>;
-			interrupts = <26 0>;
+			interrupts = <26 IRQ_TYPE_LEVEL_LOW>;
 			reg = <0x09>;
 			#clock-cells = <1>;
 
diff --git a/Documentation/devicetree/bindings/mfd/max77686.txt b/Documentation/devicetree/bindings/mfd/max77686.txt
index 42968b7144e0..4447d074894a 100644
--- a/Documentation/devicetree/bindings/mfd/max77686.txt
+++ b/Documentation/devicetree/bindings/mfd/max77686.txt
@@ -21,6 +21,6 @@ Example:
 	max77686: pmic@9 {
 		compatible = "maxim,max77686";
 		interrupt-parent = <&wakeup_eint>;
-		interrupts = <26 0>;
+		interrupts = <26 IRQ_TYPE_LEVEL_LOW>;
 		reg = <0x09>;
 	};
diff --git a/Documentation/devicetree/bindings/regulator/max77686.txt b/Documentation/devicetree/bindings/regulator/max77686.txt
index e9f7578ca09a..ff3d2dec8c4b 100644
--- a/Documentation/devicetree/bindings/regulator/max77686.txt
+++ b/Documentation/devicetree/bindings/regulator/max77686.txt
@@ -43,7 +43,7 @@ Example:
 	max77686: pmic@9 {
 		compatible = "maxim,max77686";
 		interrupt-parent = <&wakeup_eint>;
-		interrupts = <26 IRQ_TYPE_NONE>;
+		interrupts = <26 IRQ_TYPE_LEVEL_LOW>;
 		reg = <0x09>;
 
 		voltage-regulators {
diff --git a/drivers/mfd/max77686.c b/drivers/mfd/max77686.c
index 2ad554b921d9..f9e12ab2bc75 100644
--- a/drivers/mfd/max77686.c
+++ b/drivers/mfd/max77686.c
@@ -209,8 +209,7 @@ static int max77686_i2c_probe(struct i2c_client *i2c)
 
 	ret = devm_regmap_add_irq_chip(&i2c->dev, max77686->regmap,
 				       max77686->irq,
-				       IRQF_TRIGGER_FALLING | IRQF_ONESHOT |
-				       IRQF_SHARED, 0, irq_chip,
+				       IRQF_ONESHOT | IRQF_SHARED, 0, irq_chip,
 				       &max77686->irq_data);
 	if (ret < 0) {
 		dev_err(&i2c->dev, "failed to add PMIC irq chip: %d\n", ret);
-- 
2.27.0