Motorola PowerQUICC II MPC8280 Series Reference Manual page 1248

IMA Programming Model
0
Field 0
Figure 34-19. IMA Receive Group Frame Size (IGRSTATE)
Table 34-13 describes the IRGFS bit fields.
Bits Name
0 0 Reserved, initialize to zero.
1-5 — Reserved, initialize to zero.
6-7 GSC-M IMA Receive Group Frame Size
Bits 0-5: Reserved
Bits 6-7 - GSC_M: Value of received ICP cell Group Status Contl field
(Bits 1:0) which determine the IMA frame size. This field must be
programmed before links in the group are assigned
34.4.4.2.4 Receive Group Order Tables
The receive group order tables define the order of the links in the round-robin extraction of
cells to the links of the IMA group. The table consists of an array of bytes ordered from first
link to last link, with each byte providing the PHY address of its associated link. The end
of the table is indicated by an entry programmed to 0x1F.
Two group order tables are used in order to allow for on-the-fly changes (i.e. to add or
remove links), while making certain that the changes only occur at the end of a round-robin
cycle. IGRCNTL[GOTP] indicates which group order table pointer (and therefore, group
table) is currently in use. Changes should be made to the group order table not in use, and
then IGRCNTL[GOTP] should be toggled. When the current round-robin cell extraction
process completes, the next process will use the new table.
This table alone defines the order of cell extraction from the delay compensation buffers. It
is the responsibility of software to read the LIDs of the links in the group from the received
ICP cells during group startup, and to program the group order table such that its order
corresponds to the order of increasing LIDs within the group.
The format of a receive group order table entry is shown in Figure 34-20.
0
Field
Figure 34-20. Receive Group Order Table Entry
34-38
Freescale Semiconductor, Inc.
1
Table 34-13. IRGFS Field Descriptions
2
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Description
3
PHY ADDRESS
6 7
GSC-M
7
MOTOROLA