Patent ID: 8667199
Filing Date: 2014-03-04
Classification: G06F

Abstract:
1. A data processing apparatus comprising: a plurality of resources sharing a common access path; at least one logic element for issuing to said common access path access requests requesting access to said resources, each access request identifying which of said resources is to be accessed; arbitration circuitry, responsive to multiple access requests passed over said common access path, configured to perform a multi-cycle arbitration operation to arbitrate between said multiple access requests, the arbitration circuitry having a plurality of pipeline stages to allow a corresponding plurality of multi-cycle arbitration operations to be in progress at any one time, each pipeline stage performing a corresponding arbitration function such that the plurality of arbitration functions corresponding to the plurality of pipeline stages collectively perform the multi-cycle arbitration operation to select from said multiple access requests a winning access request to be granted access to its identified resource; filter circuitry having a plurality of filter states, the number of filter states being dependent on the number of pipeline stages of said arbitration circuitry, and each resource being associated with one of said filter states; for a new multi-cycle arbitration operation to be performed by said arbitration circuitry, the filter circuitry selecting one of said filter states that has not been selected for any other multi-cycle arbitration operation already in progress within the pipeline stages of the arbitration circuitry and for which the winning access request is not yet selected, determining as candidate access requests for the new multi-cycle arbitration operation those access requests that are seeking to access a resource associated with said selected filter state and providing said candidate access requests to the arbitration circuitry as said multiple access requests for the new multi-cycle arbitration operation.