Various embodiments of methods and systems for a modem-directed application processor boot flow in a portable computing device (“PCD”) are disclosed. An exemplary method includes an application processor that transitions into an idle state, such as a WFI state, for durations of time during a boot sequence that coincide with processing by a DMA engine and/or crypto engine. That is, the application processor may “sleep” while the DMA engine and/or crypto engine process workloads in response to instructions they received from the application processor.