Fan won't stop Aetina AN110

Autonomous Machines Jetson & Embedded Systems Jetson Xavier NX
1

Hello,
I have a Jetson NX with this Aetina AN110 Career board, and i can’t get my fan to stop. Rebooting the board won’t change anything.
Running tegrastats (to get the temperature of the board) gives me :

AO@22C GPU@23C PMIC@100C AUX@23C CPU@24C thermal@23.3C

I can’t use

sudo jetson_clocks --restore

since i didn’t do

sudo jetson_clocks --store

I saw that it could be related to a wrong device tree, but i don’t know how to check if this is the issue.
Any help would be appreciated.

3

hello Bazziil,

it’s Thermal Management for enabling the fan to cool-down the chip.
there’s pwm settings to control fan, you may have a try to program it through sysnode.
for example, # echo [value:0-255] > /sys/class/hwmon/hwmon2/cur_pwm
please also refer to pwm_rpm_table for a look-up table to use PWMs for controlling fan rpm,
thanks

4

Hi JerryChang,
Sorry for late reply,
I get the permission denied error with :
sudo echo 128 > /sys/class/hwmon/hwmon2/cur_pwm
I also can’t save this file after editing it with nano.
As i mentioned, the issue probably comes from the device tree, do you have any guide or documentation on how to manage device tree ?

5

hello Bazziil,

so you’re actually working with Jetson Nano? I’m moving this topic to Nano series, thanks

6

hello Bazziil,

you may check tegra_pwmfan for the sysnode for hardware monitor,

$ cat hwmon*/name
thermal-fan-est
tegra_pwmfan

it’s hwmon1 for Nano platform.
for example,

/sys/class/hwmon/hwmon1$ ls *pwm
cur_pwm  target_pwm
7

so you’re actually working with Jetson Nano? I’m moving this topic to Nano series, thanks

I should have been clearer, i meant nano the file editor, like

sudo nano sys/class/hwmon/hwmon2/cur_pwm

Result of cat hwmon*/name :
thermal-fan-est
pwm_tach
tegra_pwmfan
soctherm_oc

I only have target_pwm and cur_pwm in hwmon2 out of hwmon0/1/2/3
I can edit the file and the pwm value seems to be taken correctly (if i set target_pwm to 120, cur_pwm will be 120). But i don’t notice speed change to the fan.

8

hello Bazziil,

I see, may I have your confirmation of which Jetson platform you’re working with?
there’s pwm_rpm_table you may refer to, it shows the look-up values for RPM and PWM.
thanks

9

Hello JerryChang,
Thanks for fast reply,
I’m working on the Jetson NX with this Aetina AN110 Career board
I’m on Jetpack 4.5 on Ubuntu 18.04 LTS

10

okay, I am moving this to Jetson Xavier NX series,

11

According to pwm_rpm_table, setting pwm to 0 should stop the fan, but it doesn’t work.
I really suspect that the device tree or the drivers is the cause of the issue since cur_pwm get the correct value.
How can i check this ?

12

hello Bazziil,

did you check this by reading cur_pwm to ensure setting has applied?
this may be an issue with carrier board, please also contact with them for further investigation.
thanks

13

Hello JerryChang,

did you check this by reading cur_pwm to ensure setting has applied?

Yes, i put 120 then 0 in :

sudo nano /sys/class/hwmon/hwmon2/target_pwm

Verifying the correct value in cur_pwm with :

sudo nano /sys/class/hwmon/hwmon2/cur_pwm

It’s was 120 then 0, fan speed did not change.

please also contact with them for further investigation.

I have done it, i will try to keep you informed. Thanks for your time

14

hello Bazziil,

you may also refer to the kernel drivers for fan control.
for example,
$L4T_Sources/r32.5/Linux_for_Tegra/source/public/kernel/kernel-4.9/drivers/hwmon/pwm-fan.c

16

Hello JerryChang,
I couldn’t find that file can you point me where it is ?

17

hello Bazziil,

please download L4T Driver Package (BSP) Sources package, you shall find kernel drivers for fan control.
thanks