i'm using a teency 5v off the 3v pin and a triple sized heatsink ( down air = beneficial )
temps: 45-55...
quite a bit of heat is transferred to the underside of the board/cpu... for custom cases having a "inflow port" right under the cpu area will help alot.
After figuring out that the previous router (an oldish Belkin) was the root of conferencing problems (bufferbloat, looks like), I set up our pi4 as a wireless router. Running for 2+ days now, works great. I set up SQM as per suggestions and all problems are gone. Only worry is temperature, ranges from 64-67 (ambient here is 25-35). I have placed it on its side, in a solid plastic case (the official red/white one); when it was flat, temp went to 75+. Thanks to lockdown, I can't get any hardware over here right now... but with conferencing such a necessity, OpenWRT has been a lifesaver!
I'm using a PoE Hat instead of a power adapter. It comes with a fan but I can't control it. I've included these lines in config.txt but I see no effect
# PoE Hat Fan Speeds
dtparam=poe_fan_temp0=63000,poe_fan_temp0_hyst=3000
dtparam=poe_fan_temp1=66000,poe_fan_temp1_hyst=3000
dtparam=poe_fan_temp2=75000,poe_fan_temp2_hyst=3000
# PoE Hat Fan Speeds
dtoverlay=rpi-poe,poe_fan_temp0=63000,poe_fan_temp0_hyst=3000
dtoverlay=rpi-poe,poe_fan_temp1=66000,poe_fan_temp1_hyst=3000
dtoverlay=rpi-poe,poe_fan_temp2=75000,poe_fan_temp2_hyst=3000
Kernel 5.4.43. Is there any pkg that I need to install on top of base OpenWRT ?
you'll need to run that in config.txt on rasbian... it should setup the relevant sysfs parameters... seems that they probably use "something" to read sysfs and do the grunt work. with any luck its "sh" ( doubt it )... probably either python... a binary... ( promising to translate ) ... or heaven forbid... a driver...
edit: looks like a custom i2c driver > CONFIG_SENSORS_RPI_POE_FAN=m
edit2: these patches seem to be in the openwrt source... not sure if would need other i2c/hwmon stuff too...
kmod-hwmon-rpi-poe-fan
#######################################
# fan activation and escalation settings
dtoverlay=rpi-poe
dtparam=poe_fan_temp0=60000
dtparam=poe_fan_temp1=62000
dtparam=poe_fan_temp2=64000
dtparam=poe_fan_temp3=68000
I don't have it installed, and when using opkg install it says that a more recent kernel is required (5.4.48 instead of 5.4.43). I'll have to wait some hours until I have a maintenance window to upgrade OpenWRT.