Failed to request PPS GPIO

[khang.l4es]

Hi Community,

I connected the PPS pin of the GNSS module to the Jetson Orin Nano Devkit as below :

and configured the device-tree as following :

/ {

        pps {
                gpios = <&tegra_main_gpio TEGRA234_MAIN_GPIO(AC, 6) GPIO_ACTIVE_HIGH>;

                compatible = "pps-gpio";
                status = "okay";
        };
};

However, I got the following error :

[    1.513054] pps_core: LinuxPPS API ver. 1 registered
[    1.518017] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giometti@linux.it>
[    4.404332] pps-gpio pps: failed to request PPS GPIO
[    4.409427] pps-gpio: probe of pps failed with error -22

Should I modify the default configuration of the GPIO09 (currently SFIO) of the 40-pin header for this purpose, please ?

I am using Jetpack-5.1.2

Thanks in advance and best regards,
Khang

[KevinFFF]

Hi khang.l4es,

Could you share the result of the following command on your board?

$ sudo cat /sys/kernel/debug/gpio|grep PAC.06

@khang.l4es

Should I modify the default configuration of the GPIO09 (currently SFIO) of the 40-pin header for this purpose, please ?

and also share your configuration for this pin in pinmux spreasheet.
It should be configured as an output GPIO by default.

[khang.l4es]

Hi @KevinFFF,

Thanks for your prompt reply.

Could you share the result of the following command on your board?

$ sudo cat /sys/kernel/debug/gpio|grep PAC.06
 gpio-492 (PAC.06              )

and also share your configuration for this pin in pinmux spreasheet.
I haven’t modified this yet. I used the default of Jetson Orin Devkit (within the Jetpack-5.1.2).

Best Regards,
Khang

[khang.l4es]

Hi @KevinFFF ,

It should be configured as an output GPIO by default.

I referred to the A3 spreadsheets of the Orin Nano/NX pinmux config template and found that the relevant GPIO was configured as input :

How should I modify this to output as per your advice? Should I re-generate the .dtsi files(s) of the Orin Devkit board?

Best Regards,
Khang

[KevinFFF]

@khang.l4es

gpio-492 (PAC.06 )

It seems no other driver using the pin.

@khang.l4es

found that the relevant GPIO was configured as input :

Yes, it has been configured as input and should work with PPS signal.

You could check pps_gpio_setup() in pps-gpio.c and debug the reason about why i the pin could not be requested in driver.

[khang.l4es]

Hi @KevinFFF ,

Not sure if it was a problem of dependency order (module loading order), but when I changed the module from built-in to loadable in the kernel’s defconfig :

diff --git a/kernel/kernel-5.10/arch/arm64/configs/defconfig b/kernel/kernel-5.10/arch/arm64/configs/defconfig
index ce9f3e0a7..2c735f855 100644
--- a/kernel/kernel-5.10/arch/arm64/configs/defconfig
+++ b/kernel/kernel-5.10/arch/arm64/configs/defconfig
@@ -752,7 +752,7 @@ CONFIG_SPI_SPIDEV=m
 CONFIG_SPI_TLE62X0=m
 CONFIG_SPMI=m
 CONFIG_PPS_DEBUG=y
-CONFIG_PPS_CLIENT_GPIO=y
+CONFIG_PPS_CLIENT_GPIO=m
 CONFIG_PINCTRL_TEGRA186_DPAUX=y
 CONFIG_PINCTRL_TEGRA234_DPAUX=y
 CONFIG_PINCTRL_SINGLE=y

Then it works :

dynim@Orin-Devkit:~$ sudo dmesg | grep pps
[sudo] password for dynim: 
[    1.595449] pps_core: LinuxPPS API ver. 1 registered
[    1.600411] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giometti@linux.it>
[   13.202710] pps_core: source pps.-1 got cdev (245:0)
[   13.202716] pps pps0: new PPS source pps.-1
[   13.218508] pps pps0: Registered IRQ 297 as PPS source

Best Regards,
Khang