Watchdog on iMX7 is it PMIC or IMX2

Technical Support
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1

My plan is to start the watchdog from U-Boot, because I want to detect and resolve Linux kernel panic as well. As I read the Watchog (Linux) page, I thought this well be easy because I can start the watchdog manually in U-Boot over i2c and after Linux boots up, it takes the control over feeding it with keepalive signals.

But the reality is different. Even though Linux boots up successfully, the watchdog still resets the board. After some investigating I discovered in dmesg, that this board (iMX7D) don’t use the mentioned rn5t618-wdt in PMIC, rather imx2-wdt on SoC. Dmesg: [ 1.962425] imx2-wdt 30280000.wdog: timeout 60 sec (nowayout=0)

Maybe I misunderstood but you stated in Watchog (Linux):

On the NXP i.MX 7 based modules we make use of the PMIC watchdog, the driver is called rn5t618-wdt. The watchdog driver creates one device under /dev/watchdog. By default, the watchdog resets the system after 128 seconds.

And also in thread (Figure out reset reason) you are speaking about PMIC watchdog.

Further the Watchdog Reset is also done by the external Power Supply aka PMIC.

Did I miss something? Can you please explain me what happened to the PMIC watchdog? Why is not used on iMX7 anymore?

2

Are you building you own image or using one of our image? In a last case please specify it’s full name like

“Linux Reference Minimal
Downstream SoC vendor based kernel
Wayland/XWayland graphics back-end supported but not included
5.1.0+build.4”

3

I’m building my own based on your reference design, but that doesn’t matter because when I installed your TDX Wayland with XWayland 5.1.0+build.4 (dunfell) colibri-imx7 ttymxc0 Colibri-iMX7_Reference-Minimal-Image using Tezi the rn5t618-wdt still reset the board.

4

Sorry this thread is totally my misunderstanding.

Because I activated rn5t618-wdt in uboot, I have to feed him from userspace.

For anybody who is like me struggling with the watchdog, keep in mind that the watchdog is only loaded by kernel. If you want to use him, you have to activate and feed him from userspace (I recommend systemd).

5

HI @cicicok

Thanks for your Input.