
IDT Link Operation
PES32NT24xG2 User Manual
7 - 2
January 30, 2013
Notes
Polarity Inversion
Each port of this switch supports automatic polarity inversion as required by the PCI Express Base
Specification. Polarity inversion is a function of the receiver and not the transmitter. The transmitter never
inverts its data.
During link training, the receiver examines symbols 6 through 15 of the TS1 and TS2 ordered sets for
inversion of the PExRP[n] and PExRN[n] signals. If an inversion is detected, then logic for the receiving
lane automatically inverts received data. Polarity inversion is a lane function, not a link function. Therefore,
it is possible for some lanes of link to be inverted and for others to not be inverted.
Lane Reversal
The PCI Express Base Specification describes an optional lane reversal feature. This switch supports
the automatic lane reversal feature outlined in the specification. The operation of lane reversal is dependent
on the highest achievable link width determined dynamically by the PHY. The highest achievable link width
is the minimum of:
–
The value of the MAXLNKWDTH field in the port’s PCI Express Link Capabilities (PCIELCAP)
register.
–
The number of consecutive lanes detected by the LTSSM during the Detect state on which valid
training sets are received.
Note that the highest achievable link width is not necessarily the same as the port’s maximum link width
advertised in the PCIELCAP register. Also, note that the actual width to which the link trains may not match
the highest achievable link width (i.e, link training may fail on some lanes).
Lane reversal mapping for the various non-trivial maximum link width configurations supported by the
switch are illustrated in Figures 7.1 through 7.3. In the figures, PExRP[n] refers to the PES32NT24xG2 pin
associated with lane n of port ‘x’.
Figure 7.1 Lane Reversal for Highest Achievable Link Width of x2
PExRP[n]
PExRP[n+1]
Switch
lane 0
lane 1
(a) Port trains to x2 without lane reversal
PExRP[n]
PExRP[n+1]
Switch
lane 1
lane 0
(b) Port trains to x2 with lane reversal
PExRP[n]
PExRP[n+1]
Switch
lane 0
(c) Port trains to x1 without lane reversal
PExRP[n]
PExRP[n+1]
Switch
lane 0
(d) Port trains to x1 with lane reversal
Summary of Contents for PCI Express 89HPES32NT24xG2
Page 20: ...IDT Table of Contents PES32NT24xG2 User Manual x January 30 2013 Notes...
Page 24: ...IDT List of Tables PES32NT24xG2 User Manual xiv January 30 2013 Notes...
Page 28: ...IDT List of Figures PES32NT24xG2 User Manual xviii January 30 2013 Notes...
Page 56: ...IDT PES32NT24xG2 Device Overview PES32NT24xG2 User Manual 1 20 January 30 2013 Notes...
Page 100: ...IDT Switch Core PES32NT24xG2 User Manual 4 22 January 30 2013 Notes...
Page 128: ...IDT Failover PES32NT24xG2 User Manual 6 4 January 30 2013 Notes...
Page 148: ...IDT Link Operation PES32NT24xG2 User Manual 7 20 January 30 2013 Notes...
Page 164: ...IDT SerDes PES32NT24xG2 User Manual 8 16 January 30 2013 Notes...
Page 170: ...IDT Power Management PES32NT24xG2 User Manual 9 6 January 30 2013 Notes...
Page 196: ...IDT Transparent Switch Operation PES32NT24xG2 User Manual 10 26 January 30 2013 Notes...
Page 244: ...IDT SMBus Interfaces PES32NT24xG2 User Manual 12 40 January 30 2013 Notes...
Page 247: ...IDT General Purpose I O PES32NT24xG2 User Manual 13 3 January 30 2013 Notes...
Page 248: ...IDT General Purpose I O PES32NT24xG2 User Manual 13 4 January 30 2013 Notes...
Page 330: ...IDT Switch Events PES32NT24xG2 User Manual 16 6 January 30 2013 Notes...
Page 342: ...IDT Multicast PES32NT24xG2 User Manual 17 12 January 30 2013 Notes...
Page 344: ...IDT Temperature Sensor PES32NT24xG2 User Manual 18 2 January 30 2013 Notes...
Page 384: ...IDT Register Organization PES32NT24xG2 User Manual 19 40 January 30 2013...
Page 492: ...IDT Proprietary Port Specific Registers PES32NT24xG2 User Manual 21 44 January 30 2013 Notes...
Page 588: ...IDT NT Endpoint Registers PES32NT24xG2 User Manual 22 96 January 30 2013 Notes...
Page 710: ...IDT JTAG Boundary Scan PES32NT24xG2 User Manual 25 12 January 30 2013 Notes...
Page 743: ...IDT Usage Models PES32NT24xG2 User Manual 26 33 January 30 2013 Notes...
Page 744: ...IDT Usage Models PES32NT24xG2 User Manual 26 34 January 30 2013 Notes...