SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
Only the DPLL_PCIE_REF output CLKOUTLDO is used to supply the reference clock to the APLL input multiplexer. To adjust the output clock frequency and jitter, the following values must be programmed, dividers SD, N and M2 and the multiplier M. The values for these parameters must be programmed in the corresponding registers in PRCM as follows:
PRCM.CM_CLKSEL_DPLL_PCIE_REF[31:24] DPLL_SD_DIV - Sigma-Delta divider SD, must be set by software to ensure optimum jitter performance.
PRCM.CM_CLKSEL_DPLL_PCIE_REF[19:8] DPLL_MULT - multiplier M, multiplier factor (2 to 4095).
PRCM.CM_CLKSEL_DPLL_PCIE_REF[7:0] DPLL_DIV - dvider N, input clock divider factor (0 to 255) (actual division factor is N+1).
PRCM.CM_DIV_M2_DPLL_PCIE_REF[6:0] DIVHS - divider M2, output clock post-divider factor (1 to 127).
The state of the output clock CLKOUTLDO is indicated by the PRCM.CM_DIV_M2_DPLL_PCIE_REF[10] CLKLDOST bit.
For more details on output clock settings sequence, see Section 28.4.4.4.1.6.6, PCIe PHY DPLL Clock Programming Sequence.