Orin NX；hardware watchdog

Autonomous Machines Jetson & Embedded Systems Jetson Orin NX
1

Is the hardware watchdog integrated on the Orin NX module integrated inside the CPU or exists independently of the CPU on the module?

3

Both PMIC and Orin SoC on module have their own internal WDT.

4

What is the minimum timeout period for the hardware watchdog integrated on the Orin NX module? Millisecond level?

5

The minimum WDT period is 2ms.

7

How can I verify that the minimum timeout of the hardware watchdog integrated on the orin nx module is 2ms? Can I provide a test program? I can only set the guard dog’s feeding time to the level of seconds.

9

Please reference to this source for wdt configuration.

10

I executed this verification procedure you provided:

include <stdio.h>
include <fcntl.h>
include <stdlib.h>
include <string.h>
include <unistd.h>
include <errno.h>
include <string.h>
include <sys/ioctl.h>

include <linux/watchdog.h>

define DEV_NAME “/dev/watchdog”

int main(int argc, char **argv) {
int interval, margin;

if (argc >= 2) interval = atoi(argv[1]);
if (argc >= 3) margin = atoi(argv[2]);

printf("watchdogd started (interval %d, margin %d)!\n", interval, margin);

int fd = open(DEV_NAME, O_RDWR|O_CLOEXEC);
if (fd == -1) {
    fprintf(stderr, "watchdogd: Failed to open %s: %s\n", DEV_NAME, strerror(errno));
    return 1;
}

int timeout = interval + margin;
int ret = ioctl(fd, WDIOC_SETTIMEOUT, &timeout);
if (ret) {
    ret = ioctl(fd, WDIOC_GETTIMEOUT, &timeout);
    if (ret) {
        fprintf(stderr, "watchdogd: Failed to get timeout: %s\n", strerror(errno));
    } else {
        if (timeout > margin) {
            interval = timeout - margin;
        } else {
            interval = 1;
        }
        fprintf(stderr, "watchdogd: Adjusted interval to timeout returned by driver: timeout %d, interval %d, margin %d\n",
              timeout, interval, margin);
    }
} else {
            printf ("watchdogd: set timeout success\n");
}

    return 0;

}

The printed information is:
watchdogd started (interval -1489891884, margin 65535)!
watchdogd: Adjusted interval to timeout returned by driver: timeout 120, interval 1, margin 65535

The orin nx module restarts in the 120S.

I made changes to the program:

include <stdio.h>
include <fcntl.h>
include <stdlib.h>
include <string.h>
include <unistd.h>
include <errno.h>
include <sys/ioctl.h>
include <linux/watchdog.h>

define DEV_NAME “/dev/watchdog”

int main(int argc, char **argv) {
int interval = 10;
int margin = 5;

if (argc >= 2) {
    interval = atoi(argv[1]);
    if (interval <= 0) {
        fprintf(stderr, "Invalid interval value. It must be a positive integer.\n");
        return 1;
    }
}
if (argc >= 3) {
    margin = atoi(argv[2]);
    if (margin < 0) {
        fprintf(stderr, "Invalid margin value. It must be a non-negative integer.\n");
        return 1;
    }
}

printf("watchdogd started (interval %d, margin %d)!\n", interval, margin);

int fd = open(DEV_NAME, O_RDWR | O_CLOEXEC);
if (fd == -1) {
    fprintf(stderr, "watchdogd: Failed to open %s: %s\n", DEV_NAME, strerror(errno));
    return 1;
}

int timeout = interval + margin;
int ret = ioctl(fd, WDIOC_SETTIMEOUT, &timeout);
if (ret) {
    ret = ioctl(fd, WDIOC_GETTIMEOUT, &timeout);
    if (ret) {
        fprintf(stderr, "watchdogd: Failed to get timeout: %s\n", strerror(errno));
    } else {
        if (timeout > margin) {
            interval = timeout - margin;
        } else {
            interval = 1;
        }
        fprintf(stderr, "watchdogd: Adjusted interval to timeout returned by driver: timeout %d, interval %d, margin %d\n",
              timeout, interval, margin);
    }
} else {
    printf("watchdogd: set timeout success\n");
}

close(fd);
return 0;

}

The printed information is:
watchdogd started (interval 10, margin 5)!
watchdogd: set timeout success

The system restarts in 16s.

In addition, in the tegra_wdt.c file, I see that the minimum and maximum timeout times of the watchdog timer are set to 1 second and 255 seconds respectively.
define MIN_WDT_TIMEOUT 1
define MAX_WDT_TIMEOUT 255

Run the sudo wdctl command, and the printed information also shows that the watchdog timeout period is in seconds.
nvidia@ubuntu:~$ sudo wdctl
[sudo] password for nvidia:
Device: /dev/watchdog
Identity: Tegra WDT [version 1]
Timeout: 120 seconds
Pre-timeout: 0 seconds
FLAG DESCRIPTION STATUS BOOT-STATUS
KEEPALIVEPING Keep alive ping reply 0 0
MAGICCLOSE Supports magic close char 0 0
SETTIMEOUT Set timeout (in seconds) 0 0

How is the minimum watchdog time of 2ms achieved?