iMX8M 1PPS in

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iMX8M 1PPS in

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aaron_goldswort
Contributor I

Having difficulty getting 1PPS input on a GPIO1_IO08 tp work. My device tree fragments are:

pinctrl@30330000 {
   compatible = "fsl,imx8mm-iomuxc";
   reg = <0x0 0x30330000 0x0 0x10000>;
   pinctrl-names = "default";
   pinctrl-0 = <0x13>;

   

  ucm-imx8m-mini {

   ppsgrp {

      //
      fsl,pins = <MX8MM_IOMUXC_GPIO1_IO08_GPIO1_IO8 0x19>;
      linux,phandle = <0x60>;
      phandle = <0x60>;
   };

... etc ...

gpio@30200000 {
compatible = "fsl,imx8mm-gpio", "fsl,imx35-gpio";
reg = <0x0 0x30200000 0x0 0x10000>;
interrupts = <0x0 0x40 0x4 0x0 0x41 0x4>;
gpio-controller;
#gpio-cells = <0x2>;
interrupt-controller;
#interrupt-cells = <0x2>;
linux,phandle = <0x21>;
phandle = <0x21>;
};

... etc ...

pps {
compatible = "pps-gpio";
pinctrl-names = "default";
pinctrl-0 = <0x60>;
input-gpios = <0x21 0x08 0x01>;
assert-rising-edge;
status = "okay";
};

I have also enabled CONFIG_PPS=y and CONFIG_PPS_CLIENT_GPIO=m in the kernel config. I've compiled pps-gpio.ko against the same kernel version and .config and place it in the /lib/modules/$(uname -r)/ directory.

However during the boot process I ge the following messages:

[ 6.072774] pps-gpio pps: failed to get GPIO from device tree
[ 6.078646] pps-gpio: probe of pps failed with error -2

It would seem pretty clear that the reference to which GPIO pin to use is incorrectly configured but I can't see a problem at all. The gpios=<0x21 0x08 0x00>; should correctly point to the gpiochip0 controller pin 8 and the pinctrl fragment should select the gpio function.

There must be some core concept I'm missing here because as far as I can tell I'm doing what //linux/Documentaion/devicetree/bindings/pps/pps.txt is saying to do.

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aaron_goldswort
Contributor I

For anyone looking to do this we did get it working.

I think some of the problems we had was the yocto build environment not being ideal. So we switched to a VM using an offically supported version of ubuntu.

The solution isn't far off from my OP:

// add to pinctrl

ppsgrp {

   fsl,pins = <MX8MM_IOMUXC_GPIO1_IO08_GPIO1_IO8 0x19>;

};

// add to root

pps {
   compatible = "pps-gpio";
   pinctrl-names = "default";
   pinctrl-0 = <&ppsgrp>;
   gpios = <&gpio1 8 0>;
   status = "okay";
};

// ensure following set in kernel config

CONFIG_PPS=y

CONFIG_PPS_CLIENT_GPIO=m

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3 Replies
2,564 Views
aaron_goldswort
Contributor I

For anyone looking to do this we did get it working.

I think some of the problems we had was the yocto build environment not being ideal. So we switched to a VM using an offically supported version of ubuntu.

The solution isn't far off from my OP:

// add to pinctrl

ppsgrp {

   fsl,pins = <MX8MM_IOMUXC_GPIO1_IO08_GPIO1_IO8 0x19>;

};

// add to root

pps {
   compatible = "pps-gpio";
   pinctrl-names = "default";
   pinctrl-0 = <&ppsgrp>;
   gpios = <&gpio1 8 0>;
   status = "okay";
};

// ensure following set in kernel config

CONFIG_PPS=y

CONFIG_PPS_CLIENT_GPIO=m

2,563 Views
igorpadykov
NXP Employee
NXP Employee

Hi Aaron

I am afraid PPS drivers are not supported in nxp bsps, supported

are described in linux documentation (Release Notes, Linux Manual)

on link i.MX Software and Development Tools | NXP 

One can try to debug it using description pps drivers on

PPS - Pulse Per Second — The Linux Kernel documentation 

Best regards
igor
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hutchman
Contributor II

Igor,

So are you saying that instead of trying to figure out why my imx8mm evk 1pps signal isn't working with ptp4l very well, that I should be looking at linuxPPS instead???

Regards,

Brian

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