2024-04-25 12:29:20

by Bastien Curutchet

Subject: [PATCH v3 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.

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 <[email protected]>
---
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/[email protected]/
v2: https://lore.kernel.org/all/[email protected]/

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;
}
--
2.44.0

2024-04-25 12:42:55

by Rodolfo Giometti

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 <[email protected]>

Acked-by: Rodolfo Giometti <[email protected]>

> ---
> 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/[email protected]/
> v2: https://lore.kernel.org/all/[email protected]/
>
> 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;
> }

--
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