Freescale Semiconductor MPC8260 - Manual (Page 1134)

Inverse Multiplexing for ATM (IMA)
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
33-32 Freescale Semiconductor
Table 33-7 describes the IGTSTATE bit fields.
33.4.4.1.3 Transmit Group Order Table
The transmit group order table defines the order of the links in the round-robin distribution 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.
This table alone defines the order of cell distribution. It is the responsibility of software to program the
LID of the links in the IMA Link Table entries, 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 transmit group order table entry is shown in Figure 33-16 .
Table 33-8 describes the format of a transmit group order table entry.
0 1 2 3 4 5 6 7
Field TSTF TIMSTf GTE TRQS ELX — ICH ICPCA
Figure 33-15. IMA Group Transmit State (IGTSTATE)
Table 33-7. IGTSTATE Field Descriptions
Bits Name Description
0 TSTF TRL stuff flag. Microcode-managed parameter. Indicates that the next ICP cell on the TRL will
be part of a stuff event. Initialize to zero at group startup.
1 TIMSTF TRL imminent stuff flag. Microcode-managed parameter. Indicates that an upcoming stuff
event will be signalled in the next ICP of the TRL (via LSI=001). Initialize to zero at group
startup.
2 GTE Go to end flag - TRL has requested 2 times before round robin distribution has completed or
link will underrun and is still due a cell from round robin distribution. Microcode managed
parameter initialize to 0. Used for optional TRL Service Latency enhancement only.
3 TRQS TRL Request - TRL has requested therefore 1 round robin distribution of cells and is yet to be
completed. Microcode managed parameter initialize to 0. Used for optional TRL Service
Latency enhancement only.
4 ELX Early exit flag. Microcode-managed parameter. Initialize to zero at group startup.
5 — Reserved
6 ICH ICP change holdoff. Microcode-managed parameter. Initialize to zero at group startup.
7 ICPCA ICP change allowed flag. Microcode-managed parameter. See description of IGTCNTL[ICPC].
0 2 3 7
Field — PHY ADDRESS
Figure 33-16. Transmit Group Order Table Entry