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Message-ID: <3612b36e-3350-4a5c-827e-482434753e95@enneenne.com>
Date: Thu, 25 Apr 2024 14:42:40 +0200
From: Rodolfo Giometti <giometti@...eenne.com>
To: Bastien Curutchet <bastien.curutchet@...tlin.com>
Cc: linux-kernel@...r.kernel.org,
Thomas Petazzoni <thomas.petazzoni@...tlin.com>, herve.codina@...tlin.com,
christophercordahi@...ometrics.ca,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v3 1/1] pps: clients: gpio: Bypass edge's direction check
when not needed
On 25/04/24 14:28, Bastien Curutchet wrote:
> 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.
>
> Add a warning if irq_handler is left without triggering any PPS event.
> Bypass the edge's direction verification when info->capture_clear is not
> set.
>
> Signed-off-by: Bastien Curutchet <bastien.curutchet@...tlin.com>
Acked-by: Rodolfo Giometti <giometti@...eenne.com>
> ---
> Changes in v3:
> - Add a warning in irq_handler
> Changes in v2:
> - Modifiy the way the bypass is done to avoid code duplication
>
> v1: https://lore.kernel.org/all/20240410113502.73038-1-bastien.curutchet@bootlin.com/
> v2: https://lore.kernel.org/all/20240411061329.7262-1-bastien.curutchet@bootlin.com/
>
> drivers/pps/clients/pps-gpio.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pps/clients/pps-gpio.c b/drivers/pps/clients/pps-gpio.c
> index 2f4b11b4dfcd..af62d944d051 100644
> --- a/drivers/pps/clients/pps-gpio.c
> +++ b/drivers/pps/clients/pps-gpio.c
> @@ -52,7 +52,9 @@ static irqreturn_t pps_gpio_irq_handler(int irq, void *data)
>
> info = data;
>
> - rising_edge = gpiod_get_value(info->gpio_pin);
> + /* Small trick to bypass the check on edge's direction when capture_clear is unset */
> + rising_edge = info->capture_clear ?
> + gpiod_get_value(info->gpio_pin) : !info->assert_falling_edge;
> if ((rising_edge && !info->assert_falling_edge) ||
> (!rising_edge && info->assert_falling_edge))
> pps_event(info->pps, &ts, PPS_CAPTUREASSERT, data);
> @@ -60,6 +62,8 @@ static irqreturn_t pps_gpio_irq_handler(int irq, void *data)
> ((rising_edge && info->assert_falling_edge) ||
> (!rising_edge && !info->assert_falling_edge)))
> pps_event(info->pps, &ts, PPS_CAPTURECLEAR, data);
> + else
> + dev_warn_ratelimited(info->pps->dev, "IRQ did not trigger any PPS event\n");
>
> return IRQ_HANDLED;
> }
--
GNU/Linux Solutions e-mail: giometti@...eenne.com
Linux Device Driver giometti@...ux.it
Embedded Systems phone: +39 349 2432127
UNIX programming
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