linux-kernel - [PATCH] gpiolib: fix incorrect IRQ requesting of an active-low lineevent

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Message-ID: <20190705093031.18182-1-michael.wu@vatics.com>
Date:   Fri, 5 Jul 2019 17:30:31 +0800
From:   Michael Wu <michael.wu@...ics.com>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        <linux-gpio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <mvp.kutali@...il.com>
Subject: [PATCH] gpiolib: fix incorrect IRQ requesting of an active-low lineevent

When a pin is active-low, logical trigger edge should be inverted
to match the same interrupt opportunity.

For example, a button pushed trigger falling edge in ACTIVE_HIGH
case; in ACTIVE_LOW case, the button pushed trigger rising edge.
For user space the IRQ requesting doesn't need to do any
modification except to configuring GPIOHANDLE_REQUEST_ACTIVE_LOW.

Signed-off-by: Michael Wu <michael.wu@...ics.com>
---
 drivers/gpio/gpiolib.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index e013d417a936..b98466a05091 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -956,9 +956,11 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 	}
 
 	if (eflags & GPIOEVENT_REQUEST_RISING_EDGE)
-		irqflags |= IRQF_TRIGGER_RISING;
+		irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
+			IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
 	if (eflags & GPIOEVENT_REQUEST_FALLING_EDGE)
-		irqflags |= IRQF_TRIGGER_FALLING;
+		irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
+			IRQ_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
 	irqflags |= IRQF_ONESHOT;
 
 	INIT_KFIFO(le->events);
-- 
2.17.1