AGX Xavier: Jetpack5 Rail power iio vs hwmon

[tjk]

We are migrating from JP4.4 to JP5.0.

The 4.9 kernel had these devices:

/sys/bus/iio/devices/iio:device0 (INA3221 chip #1)
/sys/bus/iio/devices/iio:device1 (INA3221 chip #2)

The 5.10 kernel has the INA3221 chips mapped as hwmon devices instead of iio devices:

/sys/bus/i2c/drivers/ina3221/1-0040/hwmon/hwmon1/
/sys/bus/i2c/drivers/ina3221/1-0041/hwmon/hwmon2/

The JP4.4 docs explained how to read the rail power:

I can’t find any explanation in the JP5.0 docs on how to get the power measurements.

Do these need to be calculated or can they be read from somewhere?

[JerryChang]

hello tjk,

it’s change to use hwmon, you may check the sysfs with $ cat hwmon*/name to understand the rail name.
please see-also developer guide, Software-Based Power Consumption Modeling for details.
thanks

[tjk]

I guess my question is, why is there no longer a power value that can be read directly in milliwatts? Should I just do the math in userspace (i.e Power = in_current x in_voltage)?

[JerryChang]

hello tjk,

yes, please do simple math for checking milliwatts.
here’s an example to read 1-0040/channel-1, it’s voltage and current of GPU’s power rail.

$ cat /sys/bus/i2c/drivers/ina3221/1-0040/hwmon/hwmon2/in1_label
VDD_GPU_SOC
$ cat /sys/bus/i2c/drivers/ina3221/1-0040/hwmon/hwmon2/in1_input
20000
$ cat /sys/bus/i2c/drivers/ina3221/1-0040/hwmon/hwmon2/curr1_input
140

[JerryChang]

BTW, you may check Tegrastats Utility — Jetson Linux<br/>Developer Guide 34.1 documentation.
it’ll also show the runtime power consumption in milliwatts.
for example,
$ sudo tegrastats
... VDD_GPU_SOC 3200mW/3200mW VDD_CPU_CV 400mW/400mW VIN_SYS_5V0 3220mW/3220mW NC 0mW/0mW VDDQ_VDD2_1V8AO 704mW/704mW NC 0mW/0mW