DDR memory controller (MPMC)
RM0082
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Doc ID 018672 Rev 1
If the same system also contains two ports that only can request at priority level 1, the
system behavior will be slightly altered. Adding these 2 ports leads to the second priority
group structure increasing the arbitration depth.
describes this system. The text in
bold-italic (grey background)
highlights the priority level changes for P4 and P5.
To simplify, the command queue is again considered to never be full and it is assumed that
commands from ports 0, 1, 2 and 3 are only received at priority level 0. The behavior is
shown in
.
Note:
If any priority 0 port (P0, P1, P2, P3) is requesting, the system will behave as one only
priority group is acting as shown in
. Ports 4 and 5 can only win arbitration when no
higher-priority commands exist.
Table 63.
System D operation
Cycle
Ports requesting
Arbitration
winner
Next counter
Next scan order
P0
P1
P2
P3
P0
P1
P2
P3
P0-P1-P2-P3
0
Y
Y
Y
P0
1
0
0
0
P0-P1-P2-P3
1
Y
Y
Y
P0
2
0
0
0
P0-P1-P2-P3
2
Y
Y
Y
Y
P0
3
0
0
0
P0-P1-P2-P3
3
Y
Y
Y
Y
P0
4
0
0
0
P1-P2-P3-P0
4
Y
Y
Y
Y
P1
0
1
0
0
P1-P2-P3-P0
5
Y
Y
Y
Y
P1
0
2
0
0
P1-P2-P3-P0
6
Y
Y
Y
Y
P1
0
3
0
0
P2-P3-P0-P1
7
Y
Y
Y
P2
0
0
1
0
P2-P3-P0-P1
8
Y
Y
Y
P2
0
0
2
0
P3-P0-P1-P2
9
Y
Y
P3
0
0
0
1
P0-P1-P2-P3
10
Y
Y
Y
P0
1
0
0
0
P0-P1-P2-P3
11
Y
Y
P2
1
0
1
0
P0-P1-P2-P3
12
Y
Y
P2
1
0
2
0
P0-P1-P3-P2
Table 64.
System E specifications
Parameter
Port 0
Port 1
Port 2
Port 3
Port 4
Port 5
ahbX_priority0_relative_priority
4
3
2
1
1
1
ahbX_priority1_relative_priority
1
1
1
1
3
2
ahbX_port_ordering
0
1
2
3
4
5