Broadcom port on Zero W: unable to Pull.UP inputs

[wmlele]

CircuitPython version

Adafruit CircuitPython 7.2.0-alpha.1-364-g2bf5a1ee4 on 2022-02-09; Raspberry Pi Zero W with bcm2835

Code/REPL

import board
from digitalio import DigitalInOut, Direction, Pull
import time

# switch
switch = DigitalInOut(board.D19)

# if I don't do this, it won't pull the input up 
#switch.direction = Direction.OUTPUT
#switch.value = True

switch.direction = Direction.INPUT
switch.pull = Pull.UP

while True:
    print(switch.value)
    time.sleep(0.5)

Behavior

Level on D19 stays at 0V when open regardless of Pull.UP. switch.value stays False regardless of the state of the input.

If the level is first set as output, and manually set to a true value, then it stays up after reverting to input, and I can read the state.

Description

No response

Additional information

No response

[tannewt]

Do you have any experience with C on the Pi? The code for setting pulls is here: https://github.com/adafruit/broadcom-peripherals/blob/08370086080759ed54ac1136d62d2ad24c6fa267/broadcom/gpio.c#L24

Called from https://github.com/adafruit/circuitpython/blob/main/ports/broadcom/common-hal/digitalio/DigitalInOut.c#L137

I'd love help polishing up this port.

[Florin9doi]

Possible fix: Florin9doi/broadcom-peripherals@44f5392

[cleverca22]

i think that commit is about bcm2711 pulls, which differ
but the zero-w, is using the vc4 pull style, which is write-only