Some issue about pwm-fan in Jetpack 5.1.1 on Xavier NX

[ultwcz1997]

Hi, everyone,
Now I use NX in Jetpack 5.1.1 and customed board.

I found the PWM fan driver changed to kernel/kernel-5.10/drivers/hwmon/pwm-fan.c; After reading the code, it seems has not PWM signal polarity invert and tach_gpio setting.

I tested in the development Kit board, it could get the rpm of the fan by following, but in my board, it is always 0.

/sys/class/hwmon/hwmon2/rpm

So how do I change tach gpio from GPIO08(Development Kit) to GPIO12(my customed board)?

Thank you,
Best regards,
Ultwcz1997

[KevinFFF]

Hi ultwcz1997,

Are you using the same fan(as the devkit) on your custom carrier board?

@ultwcz1997

GPIO12(my customed board)?

Do you want to use the following pin as fan tach gpio?

If so, it seems not in pinmux option for ths pin.

Could you share the result of the following command on your board?

$ ls -l /sys/class/hwmon/

[ultwcz1997]

Hi @KevinFFF

Are you using the same fan(as the devkit) on your custom carrier board?

No, I want to use GPIO12 as a tach GPIO

$ ls -l /sys/class/hwmon/

lrwxrwxrwx 1 root root 0 9月   7 16:12 hwmon0 -> ../../devices/virtual/thermal/thermal_zone5/hwmon0
lrwxrwxrwx 1 root root 0 9月   7 16:12 hwmon1 -> ../../devices/platform/d280000.soctherm-oc-event/hwmon/hwmon1
lrwxrwxrwx 1 root root 0 9月   7 16:12 hwmon2 -> ../../devices/platform/39c0000.tachometer/hwmon/hwmon2
lrwxrwxrwx 1 root root 0 9月   7 16:12 hwmon3 -> ../../devices/platform/3520000.xusb_padctl/usb2-0/3520000.xusb_padctl:ports:usb2-0:connector/power_supply/usb-charger/hwmon3
lrwxrwxrwx 1 root root 0 9月   7 16:12 hwmon4 -> ../../devices/platform/pwm-fan/hwmon/hwmon4
lrwxrwxrwx 1 root root 0 9月   7 16:12 hwmon5 -> ../../devices/platform/c250000.i2c/i2c-7/7-0040/hwmon/hwmon5

If so, it seems not in pinmux option for ths pin.

Do you mean I should use a GPIO which can only configure NV_THERM_FAN_TACH

Thank you. ^_^

[KevinFFF]

@ultwcz1997

No, I want to use GPIO12 as a tach GPIO

What I want to know is that are you using the same fan module on the carrier board?

@ultwcz1997

Do you mean I should use a GPIO which can only configure NV_THERM_FAN_TACH

If you want to use other GPIO for rpm, then you should use gpio-tachometer instead of pwm-tegra194-tachometer.

[ultwcz1997]

Hi @KevinFFF

What I want to know is that are you using the same fan module on the carrier board?

Yes, the same fan module, I am so sorry to understand incorrectly.

If you want to use other GPIO for rpm, then you should use gpio-tachometer instead of pwm-tegra194-tachometer.

I will try it, thanks for your answers.

[KevinFFF]

You could refer to kernel/kernel-5.10/Documentation/devicetree/bindings/hwmon/gpio-tachometer.txt for details.

[ultwcz1997]

Okay, thank you.