After using echo 56> /sys/class/gpio/export command to control GPIO, it prompts that the device is busy

We calculated the mapping address of GPIO3_PI.00 as 56 (group=0, bank=8, offset=0) according to the guidance in the forum
But when I input echo 56> /sys/class/gpio/export, it prompts that the device is busy. What is the reason? How to solve it?
Thank you


this error shows it’s occupied by other driver or devices.
please refer to pinmux spreadsheets to review the default pin usage, you should also have pin customization with the spreadsheets.