unstability on AGX Xavier running on MAXN power mode about jetson-fan-ctl

[Pyrestone]

That sounds more like a problem with your power supply being insufficient to provide the voltage (=torque) to accelerate the fan under load.
Jetsons are known to be sensitive to voltage drop.

The voltage drop from setting the fan speed for the driver should be minimal because that's a continuous pwm signal which just changes duty cycle when the fan speed is changed. The actual motor controller hardware for fan speeds sits on the fan itself.

So I assume it's one of two things:

1. Your power supply might not be able to sustain full load on jetson + Fan without voltage drop which the jetson sees and resets.
2. The fan driver on the agx might work differently than on the nano so accessing the fan speed "file" directly might upset the driver.

[Pyrestone]

Sidenote: this tool was written for Jetson Nano and I don't have an AGX so i can't guarantee anything with regards to other devices.