Samsung S5PC100 User Manual page 313

BUS CONFIGURATION
2.2 ARBITRATION SCHEME
In the AXI interconnect, you can configure each MI separately to have an arbitration scheme that is either:
•
a non-programmable RR scheme
•
a programmable LRG scheme.
The AW and AR channels have separate arbiters and can be programmed, if applicable, and interrogated
separately through the APB programming interface, but both AW and AR channels are configured identically.
Because the AW and AR channels are arbitrated separately, an MI can permit simultaneous read and write
transactions from different SI's.
The arbitration mechanism registers the arbitration decision for use in the subsequent cycle. An arbitration
decision taken in the current cycle does not affect the current cycle.
If no SI's are active, the arbiter adopts default arbitration, that is, the highest priority SI. If this occurs and then the
highest priority interface becomes active in the same cycle as, or before any other SI, then this does not constitute
a grant to an active SI and the arbitration scheme does not change its state.
If a QoS provision is enabled and active, only a subset of SI's is permitted to win arbitration, and it cannot be
guaranteed that the default arbitration is among these. In these circumstances, no transaction is permitted to use
the default arbitration, and arbitration must occur when there is an active SI.
3.1-4
S5PC100 USER'S MANUAL (REV1.0)