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DATA SHEET
PM7367 FREEDM-32P32
ISSUE 2
PMC-1991499
FRAME ENGINE AND DATA LINK MANAGER
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMER’S INTERNAL USE
46
Field
Description
V
This bit (Valid) indicates whether a packet is currently
being received on the DMA channel. When the V bit is
set to 1, the other fields in the RCDR table entry for the
DMA channel contain valid information.
Start RPD
Pointer[13:0]
This field contains the pointer to the first RPD for the
packet being received.
DMA Current
Address[31:0]
The DMA Current Address [31:0] bits holds the host
address of the next dword in the current buffer. The
RMAC increments this field on each access to the
buffer.
8.4.2 DMA Transaction Controller
The DMA Transaction Controller coordinates the reception of data packets from
the Receive Packet Interface and their subsequent storage in host memory. A
packet may be received over a number of separate transactions, interleaved with
transactions belonging to other DMA channels. As well as sending the received
data to host memory, the DMA Transaction Controller initiates data transactions
of its own for the purposes of maintaining the data structures (queues,
descriptors, etc.) in host memory.
8.4.3 Write Data Pipeline/Mux
The Write Data Pipeline/Mux performs two functions. First, it pipelines receive
data between the RHDL block and the GPIC block, inserting enough delay to
enable the DMA Transaction Controller to generate appropriate control signals at
the GPIC interface. Second, it provides a multiplexor to the data out lines on the
GPIC interface, allowing the DMA Transaction Controller to output data relating
to the transactions the controller itself initiates.
8.4.4 Descriptor Information Cache
The Descriptor Information Cache provides the storage for the Receive Channel
Descriptor Reference (RCDR) Table described above (Figure 8).
8.4.5 Free Queue Cache
The Free Queue Cache block implements the 6 element RPDR Small Buffer
Free Queue cache and the 6 element RPDR Large Buffer Free Queue cache.
These caches are used to store free small buffer and large buffer RPDRs.