The PoE hat supported on the RPi 3B+ and 4B comes with a rather
loud fan, tripped in two steps by the brcmstb_thermal
thermal_zone driver. Enabling writable trip points allow
users to adjust the fan trip points according to their
preferred temp/noise ratio.
This setting is enabled on most other targets with similar
thermal_zone controlled cooling devices.
Signed-off-by: Bjørn Mork <bjorn@mork.no>
dabe8471fc