F.2. P-tile PCIe Design Constraints
- pin_perst_n: This is a global full reset. It resets the PHY and port controllers.
- p<n>_cold_perst_n_i: These are per-port resets, which clear the sticky bits and reset the port controller and PHY layer.
- p<n>_warm_perst_n_i: These are per-port resets, which reset the port controller and PHY layer but do not clear the sticky bits.
- pld_clrphy_n: This signal is only applicable to Port 1. It resets the PCS, PHY and port controller. It is available when the option Port 1 refclk init active is disabled in the IP Parameter Editor.
- Constraint 1: The P-tile EMIB interface operates all ports on a common system clock domain associated with PCIe Port 0. Hence, the PCIe Port 0 must be the primary endpoint.
- Constraint 2a: Port 0's reference clock must be active prior to the first pin_perst_n deassertion (i.e. cold reset exit), and should remain active while the FPGA has power (VCC_HSSI).
- Note that this typically occurs during the FPGA's initial configuration.
- Constraint 2b: Port 1's reference clock may be active prior to the first pin_perst_n deassertion (Type D only).
- Constraint 3: In PCIe modes, pin_perst_n is expected to be implemented as a "full reset", which causes a global reset and in turn reruns PHY calibration-related operations.
Constraint 4: P-tile expects the reference clock for Port 0 and Port 1 to remain active during subsequent warm reset assertions.
- Constraint 5: Implementing the independent PERST# solution will lock out the PHY Reconfiguration interface. User application logic cannot drive this interface when independent PERST# is implemented.
- The Debug Toolkit also cannot be used.
- The Hard IP Reconfiguration interface is still available.
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