[PATCH v3 1/1] pps: clients: gpio: Bypass edge's direction check when not needed

[PATCH v3 1/1] pps: clients: gpio: Bypass edge's direction check when not needed

[Bastien Curutchet]

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@bootlin.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;
 }
-- 
2.44.0

Re: [PATCH v3 1/1] pps: clients: gpio: Bypass edge's direction check when not needed

[Rodolfo Giometti]

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@bootlin.com>

Acked-by: Rodolfo Giometti <giometti@enneenne.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@enneenne.com
Linux Device Driver                          giometti@linux.it
Embedded Systems                     phone:  +39 349 2432127
UNIX programming

Re: [PATCH v3 1/1] pps: clients: gpio: Bypass edge's direction check when not needed

[Bastien Curutchet]

Hi Rodolfo

On 4/25/24 14:42, Rodolfo Giometti wrote:
> 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@bootlin.com>
> 
> Acked-by: Rodolfo Giometti <giometti@enneenne.com>
> 

I don't think I've received any updates since you acked this. Is there 
something missing before the patch can be applied?

Best regards,
Bastien

Re: [PATCH v3 1/1] pps: clients: gpio: Bypass edge's direction check when not needed

[Rodolfo Giometti]

On 26/06/24 14:55, Bastien Curutchet wrote:
> Hi Rodolfo
> 
> On 4/25/24 14:42, Rodolfo Giometti wrote:
>> 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@bootlin.com>
>>
>> Acked-by: Rodolfo Giometti <giometti@enneenne.com>
>>
> 
> I don't think I've received any updates since you acked this. Is there something 
> missing before the patch can be applied?

No updates. It can be applied.

Ciao,

Rodolfo

-- 
GNU/Linux Solutions                  e-mail: giometti@enneenne.com
Linux Device Driver                          giometti@linux.it
Embedded Systems                     phone:  +39 349 2432127
UNIX programming

Re: [PATCH v3 1/1] pps: clients: gpio: Bypass edge's direction check when not needed

[Bastien Curutchet]

Hi Rodolfo,

I revive this topic.

On 6/26/24 4:16 PM, Rodolfo Giometti wrote:
> On 26/06/24 14:55, Bastien Curutchet wrote:
>> Hi Rodolfo
>>
>> On 4/25/24 14:42, Rodolfo Giometti wrote:
>>> 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@bootlin.com>
>>>
>>> Acked-by: Rodolfo Giometti <giometti@enneenne.com>
>>>
>>
>> I don't think I've received any updates since you acked this. Is there 
>> something missing before the patch can be applied?
> 
> No updates. It can be applied.
> 

In the MAINTAINER file, you are listed as the sole maintainer for the 
PPS subsystem. Could you let me know if there's someone else in charge 
of applying patches so I can gently ping them please ?

I checked, the patch still applies to v6.13-rc1

Best regards,
Bastien

Re: [PATCH v3 1/1] pps: clients: gpio: Bypass edge's direction check when not needed

[Rodolfo Giometti]

On 04/12/24 11:34, Bastien Curutchet wrote:
> Hi Rodolfo,
> 
> I revive this topic.
> 
> On 6/26/24 4:16 PM, Rodolfo Giometti wrote:
>> On 26/06/24 14:55, Bastien Curutchet wrote:
>>> Hi Rodolfo
>>>
>>> On 4/25/24 14:42, Rodolfo Giometti wrote:
>>>> 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@bootlin.com>
>>>>
>>>> Acked-by: Rodolfo Giometti <giometti@enneenne.com>
>>>>
>>>
>>> I don't think I've received any updates since you acked this. Is there 
>>> something missing before the patch can be applied?
>>
>> No updates. It can be applied.
>>
> 
> In the MAINTAINER file, you are listed as the sole maintainer for the PPS 
> subsystem. Could you let me know if there's someone else in charge of applying 
> patches so I can gently ping them please ?
> 
> I checked, the patch still applies to v6.13-rc1

I was quite sure to have acked and then forwarded this patch to Greg and Andrew 
for the inclusion.

If not (I'm sorry), please resend the patch, and I'm going to pass it to Greg 
and Andrew right away.

Ciao,

Rodolfo

-- 
GNU/Linux Solutions                  e-mail: giometti@enneenne.com
Linux Device Driver                          giometti@linux.it
Embedded Systems                     phone:  +39 349 2432127
UNIX programming