
Chapter 8: PHY IP Core for PCI Express (PIPE) 8–17
Link Equalization for Gen3 Data Rate
November 2012 Altera Corporation Altera Transceiver PHY IP Core
User Guide
f For more information about the individual PCS blocks referenced in Table 8–11, refer
to Transceiver Architecture in Stratix V Devices or in the Stratix V Device Handbook.
Link Equalization for Gen3 Data Rate
“Section 4.2.3 Link Equalization Procedure for 8.0 GT/s Data Rate” in the PCI Express Base
Specification, Rev. 3.0 provides detailed information about the four-stage link
equalization procedure. A new LTSSM state, Recovery.Equalization with Phases 0–3,
reflects progress through Gen3 equalization. Phases 2 and 3 of link equalization are
optional; however, the link must progress through all four phases, even if no
adjustments occur. Skipping Phases 2 and 3 speeds up link training at the expense of
link BER optimization.
Gen3 requires both TX and RX link equalization because of the data rate, the channel
characteristics, receiver design, and process variations.The link equalization process
allows the Endpoint and Root Port to adjust the TX and RX setup of each lane to
improve signal quality. This process results in Gen3 links with a receiver Bit Error
Rate (BER) that is less than 10
-12
.
0x086
[31:20] R Reserved —
[19:16] R
rx_rlv
When set, indicates a run length violation.
From block: Word aligner.
[15:12] R
rx_patterndetect
When set, indicates that RX word aligner has achieved
synchronization.
From block: Word aligner.
[11:8] R
rx_disperr
When set, indicates that the received 10-bit code or data
group has a disparity error. When set, the corresponding
errdetect bits are also set.
From block: 8B/10B decoder.
[7:4] R
rx_syncstatus
When set, indicates that the RX interface is synchronized
to the incoming data.
From block: Word aligner.
[3:0] R
rx_errdetect
When set, indicates that a received 10-bit code group has
an 8B/10B code violation or disparity error. It is used
along with RX disparity to differentiate between a code
violation error and a disparity error, or both.
In PIPE mode, the PIPE specific output port called
pipe_rxstatus
encodes the errors.
From block: 8B/10B decoder.
Table 8–11. PCI Express PHY (PIPE) IP Core Registers (Part 4 of 4)
Word
Addr
Bits R/W Register Name Description
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