3. RapidIO Lanes > Lane to Port Mapping
CPS-1848 User Manual
72
June 2, 2014
Formal Status
This document is confidential and is subject to an NDA.
Integrated Device Technology
A port can operate with fewer lanes than the number assigned to it using the PWIDTH_OVRD field of the
. Examples of the use of this field are displayed in
10
-
Undefined
-
-
11
-
Undefined
-
-
Quadrant 3 / QCFG[7:6]
00
3
4x
3
12–15
7
4x
7
28–31
11
4x
11
44–47
-
-
15 (Unused)
-
01
3
2x
3
12–13
3
2x
15
14–15
7
4x
7
28–31
11
4x
11
44–47
10
-
Undefined
-
-
11
-
Undefined
-
-
1. After a configuration change is made using
Quadrant Configuration Register
, IDT recommends resetting each port as
2. After a device reset, the value of QCFG[7:0] determines the CPS-1848’s quadrant configurations. Software can also control
the quadrant configurations based on the value of QUADx_CFG in the
Quadrant Configuration Register
The least significant lane number represents the lowest lane of the port. For example, for lanes 4–7,
lane 4 is the lowest lane of the port and lane 7 is the highest lane of the port.
Table 21: PWIDTH_OVRD Examples
Maximum
Port Width
Desired
Port Width
PORT_WIDTH_
OVRD
Description
4x
2x
0b101
Use only the two lowest numbered lanes assigned to the port.
4x
1x
0b010
Use only the lowest numbered lane assigned to the port.
2x
1x
0b010
Use only the lowest numbered lane assigned to the port.
Changing the width of a port causes the port to reinitialize. For more information on the port initialization
process, see
Port and Lane Initialization Sequence
.
Table 20: Lane to Port Mapping
1
(Continued)
QUADx_CFG /
QCFG
2
Setting
PLL
Port Width
Mapping
Port
Lane(s)