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configuring gpio pin for pps-gpio on odroid c2 running 4.19.y


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A GPS module ublox is connected to a odroid c2 board on GPIOX.12 and GPIOX.13 for the RX and TX and GPIOX.10 for the PPS.

The board is running the stable kernel 4.19.42-meson64 from Armbian based on Debian stretch which was dist-upgraded to Debian buster.

I am trying to get the /dev/pps0 entry using GPIOX.10 to finish the chrony setup but I cannot find the correct syntax in the DTS file.


Any pointer or idea ?


I try either of the gpios line below, none of them seems to be correct.

pps {
  gpios = "< 0x1e 0x66 0x0 >";
  #gpios = "<&gpiox 10 GPIO_ACTIVE_HIGH>";
  #gpios = "< 0x66 >";
  compatible = "pps-gpio";

The file include/dt-bindings/gpio/gxbb.h#L122 in the Linux kernel tree show the value of GPIOX.10 is set to 102 (aka 0x66 in hexa).


After reboot, the pps-gpio module is loaded and cannot find the GPS connected.

# dmesg | grep -i pps
[    1.414780] pps_core: LinuxPPS API ver. 1 registered
[    1.414783] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giometti@linux.it>
[    5.460824] OF: /pps: could not find phandle
[    5.460835] pps-gpio pps: failed to get GPIO from device tree
[    5.460849] pps-gpio: probe of pps failed with error -22

The previous pps-gpio kernel module had the option for the gpio_pin which seems a bit easier to use :-/


Thank you.

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