linux-kernel - [PATCH 1/1] pps: clients: gpio: Bypass edge's direction check when not needed

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Date: Wed, 10 Apr 2024 13:35:02 +0200
From: Bastien Curutchet <bastien.curutchet@...tlin.com>
To: Rodolfo Giometti <giometti@...eenne.com>
Cc: linux-kernel@...r.kernel.org,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	herve.codina@...tlin.com,
	christophercordahi@...ometrics.ca,
	Bastien Curutchet <bastien.curutchet@...tlin.com>
Subject: [PATCH 1/1] pps: clients: gpio: Bypass edge's direction check when not needed

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@...tlin.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