How to access PS GPIO with PYNQ?

I have an Ultra96 V2 board running PYNQ v2.5. There are four user LEDs connected to MIO17-20 on the board. I can access BRAM by using overlay and MMIO but failed to access PS GPIO.
Thanks for help.

Info on PS GPIO here: PS GPIO — Python productivity for Zynq (Pynq)

Cathal

I tried to run:

from pynq import GPIO
output = GPIO(GPIO.get_gpio_pin(20), ‘out’)
output.write(0)

But the led didn’t change. It is same for pin 17, 18, 19.
Does it related to device tree?