Updated the Odroid U3 to (patched) Kernel 3.19, from https://github.com/tobiasjakobi/linux-odroid/tree/odroid-3.19.y
Thanks to work by tobiasjakobi, this now includes the preliminary patches – updated for 3.19 – for fan control on the Odroid U3, originally posted by Lukasz Majewski at http://www.spinics.net/lists/linux-samsung-soc/msg42259.html
So, (on a Fedora 21 system) you can now control the fan, as follows:
# echo "0" >/sys/class/hwmon/hwmon0/pwm1
– fan stops (as at boot..)
# echo "65" >/sys/class/hwmon/hwmon0/pwm1
– fan runs – at reasonable speed
# echo "255" >/sys/class/hwmon/hwmon0/pwm1
– fan runs – full speed..
Temperature can be found at
# cat /sys/devices/virtual/thermal/thermal_zone0/temp
– which returns value (with fan running) of – typically – 32000 (presumably need to divide by 1000 to get ‘degrees’ Centigrade ?)
You can check this by stopping the fan, and seeing the ‘temperature’ result increasing, and then decreasing again, when the fan is restarted..
There is some old code (license uncertain?) for automated fan/temperature control from mrdjr at hardkernel, at https://github.com/mdrjr/odroidu2-fan-service.git.. This is for an older kernel version, and (presumably) Ubuntu/Debian-centric, but it may be possible to modify and update this…
As usual, more research is needed!
Robert Gadsdon. February 10, 2015.