RM0082
DDR memory controller (MPMC)
Doc ID 018672 Rev 1
131/844
10.5.9 Error
conditions
Because of the programming difficulties of the weighted round-robin arbitration scheme, an
error reporting mechanism is included to notify users of illegal programming scenarios.
These error conditions generate a Memory Controller core interrupt and set a bit in the
wrr_param_value_err parameter to 1'b1. The potential error conditions are:
●
Bit 0 = The 5 ahbX_port_ordering parameters do not contain unique values.
●
Bit 1 = Any of the ahbX_priorityY_relative_priority parameters have been set to 10
value. A 0 value leads to unknown behavior. The minimum accepted value is 1.
●
Bit 2 = Any port, whose related bit of the weighted_round_robin_weight_sharing
parameter is set to 1'b1, do not have the same values in its
ahbX_priorityY_relative_priority parameter.
●
Bit 3 = For ports whose related bit of the weighted_round_robin_weight_sharing
parameter is set to 1'b1, the values of the ahbX_port_ordering parameters are not
sequential.
If bits 0, 2 or 3 are set to 1'b1 in the wrr_param_value_err parameter, and any of the ports
are paired in the weighted_round_robin_weight_sharing parameter, all weight sharing data
will be ignored during Memory Controller initialization and the ports will be prioritized by port
number. If port pairing is not being used, but the bit 0 error condition is set to 1'b1, then
ports with a non-unique port ordering are prioritized by port number.
Note:
The user is strongly cautioned against modifying the values of the port ordering or relative
priority parameters during active port usage.
10.5.10
Command queue with placement logic
From the Arbiter, commands are routed to the command queue of the Memory Controller
core. The command queue is fed using a placement algorithm. For more information on this
algorithm, refer to below Chapter “Core Command Queue with Placement Logic”.
7
Y
P5
1
1
1
0
1
1
P2-P0-P1-P3
P5-P4
8
Y
P4
1
1
1
0
2
2
P2-P0-P1-P3
P5-P4
9
Y
Y
P5
1
1
1
0
1
1
P2-P0-P1-P3
P5-P4
10
Y
Y
Y
P2
1
1
2
0
1
1
P0-P1-P3-P2
P5-P4
11
Y
Y
P1
2
2
0
0
1
1
P0-P1-P3-P2
P5-P4
Table 69.
System G operation (continued)
Cycle
Ports Requesting
Arbitration
Winner
Next Counter
Next Scan Order
P0 P1 P2 P3 P4 P5
P0 P1 P2 P3 P4 P5