linux-kernel - [RFC 17/18] mfd: max14577: Do not enforce (incorrect) interrupt trigger type

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Date:   Thu, 10 Dec 2020 22:25:33 +0100
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Chanwoo Choi <cw00.choi@...sung.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        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>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.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-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-rtc@...r.kernel.org
Cc:     Iskren Chernev <iskren.chernev@...il.com>,
        Matheus Castello <matheus@...tello.eng.br>,
        Sebastian Krzyszkowiak <sebastian.krzyszkowiak@...i.sm>,
        Angus Ainslie <angus@...ea.ca>,
        Hans de Goede <hdegoede@...hat.com>
Subject: [RFC 17/18] mfd: max14577: Do not enforce (incorrect) interrupt trigger type

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 14577/77836 datasheets describe 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 charger 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>

---

This patch should wait till DTS changes are merged, as it relies on
proper Devicetree.
---
 Documentation/devicetree/bindings/mfd/max14577.txt | 4 ++--
 drivers/mfd/max14577.c                             | 6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/Documentation/devicetree/bindings/mfd/max14577.txt b/Documentation/devicetree/bindings/mfd/max14577.txt
index 92070b346756..be11943a0560 100644
--- a/Documentation/devicetree/bindings/mfd/max14577.txt
+++ b/Documentation/devicetree/bindings/mfd/max14577.txt
@@ -71,7 +71,7 @@ max14577@25 {
 	compatible = "maxim,max14577";
 	reg = <0x25>;
 	interrupt-parent = <&gpx1>;
-	interrupts = <5 IRQ_TYPE_NONE>;
+	interrupts = <5 IRQ_TYPE_LEVEL_LOW>;
 
 	muic: max14577-muic {
 		compatible = "maxim,max14577-muic";
@@ -106,7 +106,7 @@ max77836@25 {
 	compatible = "maxim,max77836";
 	reg = <0x25>;
 	interrupt-parent = <&gpx1>;
-	interrupts = <5 IRQ_TYPE_NONE>;
+	interrupts = <5 IRQ_TYPE_LEVEL_LOW>;
 
 	muic: max77836-muic {
 		compatible = "maxim,max77836-muic";
diff --git a/drivers/mfd/max14577.c b/drivers/mfd/max14577.c
index be185e9d5f16..6c487fa14e9c 100644
--- a/drivers/mfd/max14577.c
+++ b/drivers/mfd/max14577.c
@@ -332,7 +332,7 @@ static int max77836_init(struct max14577 *max14577)
 	}
 
 	ret = regmap_add_irq_chip(max14577->regmap_pmic, max14577->irq,
-			IRQF_TRIGGER_FALLING | IRQF_ONESHOT | IRQF_SHARED,
+			IRQF_ONESHOT | IRQF_SHARED,
 			0, &max77836_pmic_irq_chip,
 			&max14577->irq_data_pmic);
 	if (ret != 0) {
@@ -418,14 +418,14 @@ static int max14577_i2c_probe(struct i2c_client *i2c,
 		irq_chip = &max77836_muic_irq_chip;
 		mfd_devs = max77836_devs;
 		mfd_devs_size = ARRAY_SIZE(max77836_devs);
-		irq_flags = IRQF_TRIGGER_FALLING | IRQF_ONESHOT | IRQF_SHARED;
+		irq_flags = IRQF_ONESHOT | IRQF_SHARED;
 		break;
 	case MAXIM_DEVICE_TYPE_MAX14577:
 	default:
 		irq_chip = &max14577_irq_chip;
 		mfd_devs = max14577_devs;
 		mfd_devs_size = ARRAY_SIZE(max14577_devs);
-		irq_flags = IRQF_TRIGGER_FALLING | IRQF_ONESHOT;
+		irq_flags = IRQF_ONESHOT;
 		break;
 	}
 
-- 
2.25.1