7.8.5. Flushing

Flushing is the emptying of existing data from the trace source buffers before tracing new data begins. See the CoreSight Architecture Specification for more on flushing mechanisms. At all times during a flushing operation, all ATB signals must comply with the ATB protocol.

The behavior of the CSTF is that AFREADYM only responds HIGH when all Slave ports have returned AFREADYS HIGH.

On assertion of AFVALIDM to the CSTF, all the enabled slave ports must have their AFVALIDS signals asserted to ensure that the marker for flushing historical information is located at similar times. AFVALIDS must then remain asserted until the specific slave port responds with AFREADYS HIGH. AFVALIDS is deasserted on a port by port basis.

The CSTF flushing mechanism uses the funnel prioritization for flushing historical data from components connected to the funnel inputs.

When AFVALIDS is output HIGH on all CSTF slave ports, the first source to indicate that it has valid data, indicated by ATVALIDS HIGH, is accepted.

If multiple sources assert ATVALIDS HIGH on the same cycle, then the highest priority source is selected. When this source completes other sources can be serviced.

When the flush is complete for a particular trace source, it is ignored in the input selection priority selection scheme until all enabled inputs have completed the flush operation by returning AFREADYS HIGH. This occurs even if it might have more data available, that is, ATVALID is HIGH.

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