3. Serial RapidIO Electrical Interface > Port Aggregation: 1x and 4x Modes
68
Tsi578 User Manual
June 6, 2016
Integrated Device Technology
www.idt.com
Figure 13: Port Configuration
3.3
Port Aggregation: 1x and 4x Modes
The RapidIO ports on the Tsi578 are grouped into pairs that share the same MAC. The MAC provides
the PMA/PCS encoding/decoding layers, as well as the RapidIO physical, transport and logical layer
functionality required of a RapidIO switch device.
The MACs are numbered by even numbers and support the ports in the following manner: serial ports
0 and 1 use MAC 0, ports 2 and 3 use MAC 2, etc. Ports are grouped into pairs of N and N+1, where N
is even.
Two configurations are possible on each 4x mode-capable port:
•
Both port N and port N+1 can operate in 1x mode (the 1x + 1x configuration)
•
Port N can operate in 4x while port N+1 is unused and can be powered down (the 4x + 0x
configuration)
Each Tsi578 MAC has an external pin called SPx_MODESEL. This pin can be pulled high to configure
the MAC for either 1x + 1x mode or pulled low for 4x + 0x mode (see
). These
pins are sampled after reset is de-asserted. To ensure that the pins are sampled correctly, the pins must
be stable at the release of reset, and held at a stable level for 10 clock cycles after reset is de-asserted.
The sampled state of the pins is reflected in the PORT_WIDTH field in the
After reset, the configuration mode can be re-programmed by changing the MAC_MODE field in the
“SRIO MAC x Digital Loopback and Clock Selection Register” on page 377
and the programmed
value overrides the pin setting of SPx_MODESEL. Changes to the MAC_MODE field that are
different than that set by the SPx_MODESEL pin must be programmed after a hardware or software
reset with a register write in order to restore the desired condition.
Ti
p
1x mode
means that one physical SerDes lane is used between link partners, and
4x mode
means that four physical lanes are used between link partners. 4x mode offers four times the
bandwidth as 1x mode at the same baud rate.
SP0
(4x or 1x)
SP1
(1x only)
Tx(Lane A,B,C,D)
Rx(Lane A,B,C,D)
X
4x Mode
SP0
(4x or 1x)
SP1
(1x only)
Dual 1x Mode
OR
Tx(Lane A)
Rx(Lane A)
Tx(Lane B)
Rx(Lane B)
Port 0
Port 1
Port 0