Know problem. I tried to activate GPIOs, but received:
root@OpenWrt:/sys/class/gpio# echo 1 > export
ash: write error: Resource busy
etc.. kernel log shows GPIOs:
[ 0.633698] rt2880_gpio 10000600.gpio: registering 24 gpios
[ 0.639155] rt2880_gpio 10000600.gpio: registering 24 irq handlers
[ 0.645456] rt2880_gpio 10000688.gpio: registering 1 gpios
[ 0.650784] rt2880_gpio 10000688.gpio: registering 1 irq handlers
[ 0.863099] gpio-export gpio_export: 1 gpio(s) exported