amdgpu reported fan speed looks too high (dual fan Sapphire Pulse Vega 56 and Sapphire RX 5700 XT)

Submitted by Shmerl @shmerl

Assigned to Default DRI bug account

Link to original bug (#105718)

Description

I have Sapphire Pulse Vega 56, which ships with two fans. According to this: https://www.youtube.com/watch?v=3mKSrSluxbM&t=1m25s
in a normal scenario, fans should spin at under 650 RPM. However sensors report for idle load around 1280 RPM for me, which looks like a double value of the above:

amdgpu-pci-2f00
Adapter: PCI adapter
fan1: 1281 RPM
temp1: +29.0°C (crit = +0.0°C, hyst = +0.0°C)

pwm1 is set to auto:

sudo cat /sys/class/drm/card0/device/hwmon/hwmon3/pwm1_enable
2

Is this a misdetection, or it's supposed to be like that? Actual fans are pretty silent.

System: Debian testing, x86_64 (kernel 4.15.4).