MIPI D-PHY IP User Guide: Agilex™ 3 and Agilex™ 5 FPGAs

ID 817561
Date 3/30/2025
Public

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7.5. CSR Clock Domain Crossing (CDC)

The D-PHY IP has a few clock domain crossings. The most major one is between the regfile’s axi_clk and the rest of the D-PHY PCS.

Most of the control registers from the regfile CSR are not synchronized to the destination clock domains. To ensure proper synchronization, observe the following sequence when updating any control registers (this excludes clearing status registers):

  1. Disable D-PHY by writing a 0 to D-PHY_CSR.Enable (offset 0x10 bit 0).
  2. Update control registers.
  3. Enable D-PHY by writing a 1 to D-PHY_CSR.Enable (offset 0x10 bit 0).

Alternatively, to use the link’s data lane 0’s PPI.Enable signal to reset the D-PHY link when updating the control registers.