SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
Idle-bypass fast relock mode is not supported for DPLL_PCIE_REF.
DPLL_PCIE_REF supports idle-bypass low-power mode. A transition from a normal operation to idle-bypass mode is performed when software sets the PRCM.CM_CLKMODE_DPLL_PCIE_REF[2:0] DPLL_EN bit field to 0x5. IDLE signal assertion triggers a power-down sequence on DPLL internal LDO analog blocks and the DCO oscillator. This mode is also the default state after PRCM reset for the DPLL_PCIE_REF.
In idle-bypass low-power mode, the CLKOUTLDO goes low. Also, the internal reference clock REFCLK = CLKINP/N + 1 is gated inside the DPLL digital control logic to save power, the internal LDO and the DCO are turned off.
To exit idle-bypass mode and restore clock generation, the user should write PRCM.CM_CLKMODE_DPLL_PCIE_REF[2:0] DPLL_EN bit field to 0x7, which deasserts the IDLE signal, and DPLL_PCIE_REF automatically enters a relock sequence. CLKOUTLDO output clock is activated after DPLL_PCIE_REF enters locked mode.