Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | Date | Wed, 10 Apr 2024 17:24:36 +0200 | Subject | Re: [PATCH 1/1] pps: clients: gpio: Bypass edge's direction check when not needed | From | Rodolfo Giometti <> |
| |
On 10/04/24 16:46, Bastien Curutchet wrote: > Hi Rodolfo, > > On 4/10/24 16:23, Rodolfo Giometti wrote: >> On 10/04/24 13:35, 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. >>> >>> 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)) >> >> Apart the code duplication, which are the real benefits of doing so? >> > > It prevents from losing a PPS event when the pulse is so short (or the > kernel so busy) that the trailing edge of the pulse occurs before the > interrupt handler can read the state of the GPIO pin.
Have you a real case when this happens?
In any cases we should avoid code duplication... so I think we should do something as below:
diff --git a/drivers/pps/clients/pps-gpio.c b/drivers/pps/clients/pps-gpio.c index 2f4b11b4dfcd..f05fb15ed7f4 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); + 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); Please, review and test it before resubmitting. :)
Ciao,
Rodolfo
-- GNU/Linux Solutions e-mail: giometti@enneenne.com Linux Device Driver giometti@linux.it Embedded Systems phone: +39 349 2432127 UNIX programming
| ![\](/images/icornerr.gif) |