Equalization Sequences - 1.0 English

Versal Adaptive SoC PHY for PCI Express LogiCORE IP Product Guide (PG345)

Document ID
PG345
Release Date
2024-06-05
Version
1.0 English

This section describes the equalization sequences of the PCIe PHY IP.

Preset Apply During Speed Change

The following figure shows the TX Equalization interface signals during the speed change. It includes Preset Apply (phy_txeq_ctrl = 2'b01) and Coefficient Query (phy_txeq_ctrl = 2'b11). The speed change is performed in LTSSM Recovery. Speed and LTSSM Polling.Compliance states. Preset Apply step must be performed after asserting phy_txelecidle and before driving phy_rate to the new speed.

Figure 1. TX Equalization Interface Signals during Speed Change (Preset Apply)

RX Adapt

The following figures describe the RX Equalization interface signals during the RX Adapt. RX Adapt is performed in Phase 2 of the LTSSM Recovery. Equalization state for the Upstream Port and Phase 3 of the LTSSM Recovery. Equalization state for the Downstream Port. It is composed of two steps: a) New Proposal, and b) Adaptation, in that order.

The following figure shows the New Proposal step where RX purposes a new preset (phy_rxeq_done = 1'b1 and phy_rxeq_adapt_done = 1'b0) upon a TX preset request (phy_rxeq_txpreset with phy_rxeq_ctrl= 2'b10).

Figure 2. RX Equalization Interface Signals during RX Adapt (New Proposal)

The following figure shows the Adaptation step where RX adapts the preset (phy_rxeq_done = 1'b1 and phy_rxeq_adapt_done = 1'b1) which TX requests (phy_rxeq_txpreset with phy_rxeq_ctrl= 2'b10).

Figure 3. RX Equalization Interface Signals during RX Adapt (Adapted)

TX Adapt

The following figures describe the TX Adapt steps. TX Adapt is performed in Phase 3 of the LTSSM Recovery. Equalization state for the Upstream Port and Phase 2 of the LTSSM Recovery. Equalization state for the Downstream Port.

The following figure shows the TX Adapt step when receiving Preset. It includes Preset Apply (phy_txeq_ctrl = 2'b01) and Coefficient Query (phy_txeq_ctrl = 2'b11).

Figure 4. TX Equalization Interface Signals during TX Adapt (Preset)

The following figure shows the TX Adapt step when receiving Coefficients. It includes Coefficient Apply (phy_txeq_ctrl =2'b10) and Coefficient Query (phy_txeq_ctrl = 2'b11).

Figure 5. TX Equalization Interface Signals during TX Adapt (Coefficients)