The fan rpm cannot be detected

The PWM and RPM of the fan were detected normally, but after one time a power-on, the RPM could not be detected and was always displayed as 0, and the PWM remained 100%.
Like this:
Is there any way to solve this problem?

Hi 1415281912,

Are you using the devkit or custom board for AGX Orin?
What’s your Jetpack version in use?

Is your fan still spinning when you see 0 rpm?

It’s custom board for AGX Orin and Jetpack version is 5.0.2.
Yes, the fan is still spinning, at full speed.

I will suggest verify with the latest JP5.1.2(R35.4.1).

Could you share the result of the following command?

$ ls -l /sys/class/hwmon/

But until then JP5.0.2 is fine, rpm can detected.

Could you share the result of the following command when you see rpm showing zero in GUI?

$ cat /sys/devices/platform/39c0000.tachometer/hwmon/hwmon0/rpm


Could you also share the result of the following command?

$ sudo apt-get install devmem2
$ sudo devmem2 0x02430050


It seems not the expected value and it should be 0x1451.
Could you use the following command to write this register?

$ sudo devmem2 0x02430050 w 0x1451

OK. It seems to write successfully

Does your rpm value still report 0 when the fan is spinning?

Yes. It still report 0.

Could you modify the register value to 0x1459 and read the rpm again?

$ sudo devmem2 0x02430050 w 0x1459
$ sudo devmem2 0x02430050
$ cat /sys/devices/platform/39c0000.tachometer/hwmon/hwmon0/rpm

Yeah, but it doesn’t seem to be working.

I tried it on another machine with the same custom board and system but no rpm problem, 0x02430050 has the same value.
I think the original value of the machine with the rpm problem should also be 0x1455, but I don’t know why the rpm is always 0.

Do you mean the issue happen on the specific module with the same carrier board?

Yes, it seems to be a problem with the module.

Maybe you could try to put this module on the devkit and check if there’s the same issue.

Now there is no devkit on hand, but through the cross-verification of the custom board and module, it can be determined that the module is the problem, but it is not clear what causes this problem.