GPIO pullups not working

[Elwood Downey]

Hello all;

Using RELEASE-13 on Raspberry Pi 4 I can not seem to engage GPIO input
pullups. Doing so should cause an input not connected to anything to read
high but it always reads low. Connecting the pin to 3.3V does read hi so I
know the pin is working correctly as an input, just that the pullup is not
connecting.

I configure the pin as follows:

freebsdpi# gpioctl -c 21 PU IN
freebsdpi# gpioctl -l | grep 21
pin 21: 0 pin 21<IN,PU>
freebsdpi# sysctl dev.gpio.0.pin.21.function
dev.gpio.0.pin.21.function: input

# test with pin disconnected
freebsdpi# gpioctl 21
0

Now connecting to 3.3V:
freebsdpi# gpioctl 21
1

Installing a microSD with Raspbian Buster in the same Pi, I can repeat the
above using their tools and the pullup works as expected, so I know the
hardware is fine.

Any help appreciated, advTHANKSance

Elwood Downey
Tucson AZ