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SubjectRe: [PATCH] pps-gpio: use IRQ edge config when not capturing both edges
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On 08/09/2017 21:53, Tim Harvey wrote:
> PPS signals with very short pulse-widths can be missed if their state
> changes by the time the interrupt handler reads the GPIO pin state.
>
> To avoid this in the case where we are only looking for one edge we can
> use the edge configuration for the pin state but fall back to reading the
> pin if both edges are being watched.

I disagree. The "rising_edge" status should be get from the hardware and not
derived by an empirical computation. Or, at least, it should be specifically
activated by setting something like this:

pps {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_pps>;

gpios = <&gpio1 26 GPIO_ACTIVE_HIGH>;
Yes-I-want-get-signal-status-in-an-epirical-way;

compatible = "pps-gpio";
status = "okay";
};

This setting should also print a warning in order to be clear for the user that
he/she should know what he/she is doing.

Then the code should check also the compatibility with property
"assert-falling-edge"...

Ciao,

Rodolfo

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