PCI Express Switch Port Use Mode - 3.4 English

Versal Adaptive SoC CPM Mode for PCI Express Product Guide (PG346)

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Basic PCI Express Two Port Switch Use Case

PCIe switches feature a single upstream port linking to the Rootport, multiple downstream ports linking to devices along with a switching mechanism that is responsible for directing the data packets among these ports.

The following figure shows a PCI Express two port switch use case consisting of a PCI Express upstream port connecting to a soft switching logic which in turn connects to a single downstream port. CPM PCIe controller supports both upstream and downstream modes and each of these blocks has four separate data interfaces on its client side based on the AXI4-Stream protocol. The switching logic needs to be implemented in a soft logic which manages the routing of packets directing them from downstream to upstream ports or vice versa. It needs to ensure that the bandwidth aligns between the upstream and downstream ports and additionally any required data interface conversions.

Note: The switch logic is not provided by AMD with the CPM core, a reference design will be provided in a later release. Contact AMD Support for more information.
Figure 1. Basic Use Case Illustration of Upstream and Downstream Ports