i.MX ProcessorsのトピックRe: iMX8M 1PPS in

iMX8M 1PPS in

aaron_goldswort — Tue, 26 May 2020 05:53:43 GMT

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.

Re: iMX8M 1PPS in

igorpadykov — Tue, 26 May 2020 23:33:20 GMT

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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Re: iMX8M 1PPS in

aaron_goldswort — Wed, 17 Jun 2020 02:26:40 GMT

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

Re: iMX8M 1PPS in

hutchman — Fri, 29 Jan 2021 01:00:04 GMT

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