linux-kernel - [PATCH 08/22] gpiolib: cdev: complete the irq/thread timestamp handshake

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Date:   Tue, 23 Jun 2020 12:00:53 +0800
From:   Kent Gibson <warthog618@...il.com>
To:     linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        bgolaszewski@...libre.com, linus.walleij@...aro.org
Cc:     Kent Gibson <warthog618@...il.com>
Subject: [PATCH 08/22] gpiolib: cdev: complete the irq/thread timestamp handshake

Reset the timestamp field to 0 after using it in lineevent_irq_thread.

The timestamp is set by lineevent_irq_handler and is tested by
lineevent_irq_thread to determine if it is called from a nested theaded
interrupt.
lineevent_irq_thread is assuming that the nested, or otherwise, status
of the IRQ is static, i.e. it is either always nested or never nested.
This change removes that assumption, resetting the timestamp so it can
be re-used to determine the nested state of subsequent interrupts.

Signed-off-by: Kent Gibson <warthog618@...il.com>

---
 drivers/gpio/gpiolib-cdev.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index d50339ef6f05..1e8e0a0a9b51 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -559,6 +559,8 @@ static irqreturn_t lineevent_irq_thread(int irq, void *p)
 	else
 		ge.timestamp = le->timestamp;

+	le->timestamp = 0;
+
 	if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE
 	    && le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE) {
 		int level = gpiod_get_value_cansleep(le->desc);
-- 
2.27.0