Can't get GPIO PPS to work

Autonomous Machines Jetson & Embedded Systems Jetson TX2
1

Forgive me if this is obvious; I am new to this device tree stuff.

I am trying to use the gps_ppio module with the signal GPIO_EXP0_INT (GIPIOY offset 4).

My currently installed device tree (obtained via dtc -I fs -O dts -o extracted_proc.dts /proc/device-tree) includes:

pps {
	gpios = <0x12 0xa0 0x0>;
	compatible = "pps-gpio";
	status = "okay";
};

When I load the gpio_pps module, dmesg shows:

OF: /pps: could not get #gpio-cells for /bpmp_i2c/spmic@3c/regulators/sd2
[ 879.622884] pps-gpio pps: failed to get GPIO from device tree
[ 879.628747] pps-gpio: probe of pps failed with error -22

What am I doing wrong ?

  • Bob
2

You may need to enable pps config in kernel config too.

https://devtalk.nvidia.com/default/topic/1068385/jetson-tx2-nano-pps-gpio-configuration/

3

I already confirmed that PPS is configured in the kernel.

Should I be concerned that decompiling the existing device tree gives about a hundred warnings ?

  • Bob
4

It appears I miscalculated based on an example from an earlier kernel; I should have used

gpios = <0x1b 0xa0 0x0>;