Hello,
If the external POR_B signal is not used (always held high or left unconnected), the processor defaults to the internal POR function (PMU controls generation of the POR based on the power supplies). There is no need to configure it.
i.MX6ULL has a module that generates an internal POR_B signal that is logically AND'ed with any externally applied SRC_POR_B signal. The internal POR_B signal will be held low until all of the following conditions are met:
• 4ms after the external power supply VDDHIGH_IN is valid
• 1ms after the VDD_SOC_CAP supply is valid:
Best regards.