Messages in this thread | | | Subject | Re: [PATCH] pps-gpio: use IRQ edge config when not capturing both edges | From | Rodolfo Giometti <> | Date | Sun, 10 Sep 2017 12:43:58 +0200 |
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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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