I'm not using USB nor ADC/DAC on the STM32MP157A. Can I tie VDDA, OTG_VBUS, AND VDD3V3_USBxS to circuit ground (VSS)?
If I'm interpreting Table 13 correctly (datasheet p 128), VDDA can be set to 0 volts provided VREF is not used. Similarly power pins related to USB can also be set to 0 volts. Looking in the datasheet p29,I just need to star-connect VDD_ANA, VDD_PLL...