I would like pins 20 and 21 to be used only for I2C. I used the device tree configuration tool to enable I2C on these pins and I2C seems to work just fine. However, I noticed that users can still go into /sys/class/gpio and control pins 20 and 21 (GPIO92 and GPIO85) as GPIOs. I modified imx6qdl-udoo-externalpins.dtsi so that EIM_D28 and EIM_D21 were no longer configured as GPIOs under hoggrp-2. I enabled i2c1 and made sure that EIM_D28 and EIM_D21 were configured for I2C in the other relevant device tree source files. Again, I2C seems to work just fine with these changes, but I can still control pins 20 and 21 as GPIOs under /sys/class/gpio. Is there a way for pins 20 and 21 to not be enumerated under /sys/class/gpio if they are configured to be used for I2C?