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.
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).
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).
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 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).
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).
