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From: Bastien Curutchet <bastien.curutchet@bootlin.com>
To: Rodolfo Giometti <giometti@enneenne.com>
Cc: linux-kernel@vger.kernel.org,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	herve.codina@bootlin.com,
	christophercordahi@nanometrics.ca,
	Bastien Curutchet <bastien.curutchet@bootlin.com>
Subject: [PATCH 1/1] pps: clients: gpio: Bypass edge's direction check when not needed
Date: Wed, 10 Apr 2024 13:35:02 +0200
Message-ID: <20240410113502.73038-1-bastien.curutchet@bootlin.com>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

In the IRQ handler, the GPIO's state is read to verify the direction of
the edge that triggered the interruption before generating the PPS event.
If a pulse is too short, the GPIO line can reach back its original state
before this verification and the PPS event is lost.

This check is needed when info->capture_clear is set because it needs
interruptions on both rising and falling edges. When info->capture_clear
is not set, interruption is triggered by one edge only so this check can
be omitted.

Bypass the edge's direction verification when info->capture_clear is not
set.

Signed-off-by: Bastien Curutchet <bastien.curutchet@bootlin.com>
---
 drivers/pps/clients/pps-gpio.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/pps/clients/pps-gpio.c b/drivers/pps/clients/pps-gpio.c
index 2f4b11b4dfcd..c2a96e3e3836 100644
--- a/drivers/pps/clients/pps-gpio.c
+++ b/drivers/pps/clients/pps-gpio.c
@@ -52,6 +52,15 @@ static irqreturn_t pps_gpio_irq_handler(int irq, void *data)
 
 	info = data;
 
+	if (!info->capture_clear) {
+		/*
+		 * If capture_clear is unset, IRQ is triggered by one edge only.
+		 * So the check on edge direction is not needed here
+		 */
+		pps_event(info->pps, &ts, PPS_CAPTUREASSERT, data);
+		return IRQ_HANDLED;
+	}
+
 	rising_edge = gpiod_get_value(info->gpio_pin);
 	if ((rising_edge && !info->assert_falling_edge) ||
 			(!rising_edge && info->assert_falling_edge))
-- 
2.44.0