3. Serial RapidIO Electrical Interface > Port Lanes
75
Tsi578 User Manual
June 6, 2016
Integrated Device Technology
www.idt.com
In 4x mode, the default state of the odd numbered port is powered on. All registers in the even and odd
numbered port are accessible but the odd numbered port does not have access to the PHY. In order to
decrease the power dissipation of the port, the odd numbered port can be powered down in this
configuration. When the even numbered port is operating in 1x mode it uses only Lane A and the odd
numbered port is permitted to operate in 1x mode using Lane B.
For more information on lanes, refer to
“Lanes and Channels” on page 76
.
3.6.1
Lane Synchronization and Alignment
When coming out of reset, the transmit side of the port must continuously send out /K28.5/ code groups
on each lane to assist the receive side of its link partner to synchronize. Once a /K28.5/ code group is
detected by the receive port, another 127 /K28.5/ code groups must be received error free before the
receive port can declare that it is synchronized. No other useful information is communicated between
the link partners until the ports are synchronized.
For a 4x port, after lane synchronization is complete, lane alignment starts. The port transmits /A/’s
(||A||) on all four lanes, according to the
RapidIO Interconnect Specification (Revision 1.3)
idle
sequence generation rules. Reception of four ||A||’s without the intervening reception of a misaligned
column is the condition for achieving lane alignment. A misaligned column (that is a column with at
least one ||A|| but not all ||A||s in a row) causes the alignment process to restart. Bit errors, or receptions
of rows without all /A/’s, result in sampling/buffering adjustments in an attempt to achieve alignment.
For more information, see the
RapidIO Interconnect Specification (Revision 1.3).
3.6.2
Lane Swapping
Lane swap
is the ability to reverse the order of the transmit and receive pins. The Tsi578 allows the
order of the transmit and/or receive pins of each 4x port to be reversed in order to simplify board layout
issues. Lane swap is only supported when the MAC is operating in 4x mode.
Lane swapping for 1x mode is not supported. If the Tsi578 port to a connector is lane swapped as 4x
mode and a 1x mode device in inserted into the connector, the 4x mode port will fail-down (that is,
become a 1x mode connection) and lane A is initialized. However, if the Tsi578 port to a connector is
lane swapped as 4x mode and then re-configured to operate as a 1x mode, the swapping is canceled and
the port will be unable to connect to a 1x mode device.
shows the lane sequence for Tsi578’s swapped 4x mode lanes, the connector, and the sequence
for non-swapped 1x mode lanes.
Table 7: Lane Sequence
Swapped 4x Mode
Mated Connector
Unswapped 1x Mode
Lane Sequence
Lane Sequence
Lane Sequence
D
D
A
C
C
B