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3. Serial RapidIO Electrical Interface > Clocking
69
Tsi574 User Manual
June 6, 2016
Integrated Device Technology
www.idt.com
The two ports that share the same MAC also share the same transmit clock, which means the two ports
must have the same bit rate. To select the bit rate, write the IO_SPEED field (see
Digital Loopback and Clock Selection Register” on page 369
), as described in
.
The initial clock rate is selected by the global power-up option for all ports.
3.3.2
4x Configuration
When the even-numbered port in a Tsi574 MAC is configured to operate in 4x mode (for example port
0), the odd-numbered port in a MAC (for example port 1) cannot be used and the register values for the
odd-numbered port should be ignored. To save power, the odd-numbered port can be powered down
(see
).
The even-numbered port configured for 4x mode follows the link-width negotiation rules outlined in
the
RapidIO Interconnect Specification (Revision 1.3)
. Depending on the configuration or capabilities
of the link partner, or on the quality of the connection, it is possible that a port configured for 4x mode
actually operates in 1x mode on either SerDes lane A or C. Under this scenario, the degraded port can
not be configured to an 1x + 1x mode.
System software can force a downgrade in port mode by writing the OVER_PWIDTH field on either
the Tsi574 or in its link partner (see
“RapidIO Serial Port x Control CSR” on page 273
). The current
operating link width is available in the INIT_PWIDTH field. Software may need to manage ackID
recovery for the link partner when changing port usage between lanes A and C.
3.3.2.1
Degraded Link Mode
When a 4x port has degraded to a 1x mode, software may attempt to recover to 4x mode by using the
FORCE_REINIT bit in the
“RapidIO Port x Control Independent Register” on page 311
3.4
Clocking
Serial RapidIO ports use source clocked transmission; the clock is embedded in the data stream using
8B/10B encoding. The Tsi574 recovers the embedded clock in the received data stream and generates a
separate clock (based on S_CLK) to transmit its own data.
The unusable, odd-numbered port is still a part of the Tsi574’s memory map. However,
system software must be aware that the port is not usable and that its per-port registers should
not be accessed. If the port is accessed the Tsi574’s behavior is undefined. Refer to
for more details on register behavior under power down conditions.
It is necessary to know if the link partner can continue to communicate when changing the
port width between Lanes A and C. Refer to the
“RapidIO Serial Port x Control CSR”
in the
link partner to determine the capability of the link partner.
Connecting four 1x links to a 4x port is not supported. Doing so results in the port failing to
achieve lane alignment.
Содержание IDT Tsi574
Страница 1: ...IDT Tsi574 Serial RapidIO Switch User Manual June 6 2016 Titl...
Страница 20: ...About this Document 20 Tsi574 User Manual June 6 2016 Integrated Device Technology www idt com...
Страница 34: ...1 Functional Overview JTAG Interface 34 Tsi574 User Manual June 6 2016 Integrated Device Technology www idt com...
Страница 100: ...4 Internal Switching Fabric Packet Queuing 100 Tsi574 User Manual June 6 2016 Integrated Device Technology www idt com...
Страница 224: ...11 Signals Pinlist and Ballmap 224 Tsi574 User Manual June 6 2016 Integrated Device Technology www idt com...
Страница 490: ...B Clocking P_CLK Programming 490 Tsi574 User Manual June 6 2016 Integrated Device Technology www idt com...
Страница 512: ...Index 512 Tsi574 User Manual June 6 2016 Integrated Device Technology www idt com...