The K24 SOM provides the mechanisms to power down all SOM power rails including the PL power domain from a dedicated pin, carrier board input, and software via the Zynq UltraScale+ MPSoC power management unit (PMU). The MIO34 pin on the Zynq UltraScale+ MPSoC is connected to the power shutdown request of the SOM power sequencer on the board. The power sequencer device sequences down all supplies when it observes a transition from a logic-High to a logic-Low state. On power up, the power sequencer ignores the shutdown request signal until after the POR_B is released. For additional PMU firmware guidance, see the Kria SOM Wiki.
The K24 SOM can also use the PMU-based PL power domain control. See Zynq UltraScale+ MPSoC: Software Developers Guide (UG1137) for more information.