Motorola PowerQUICC II MPC8280 Series Reference Manual page 1276

IMA Software Interface and Requirements
6. Program the ICP offset (ILTTE): LICPOS = x.
7. Initialize the Transmit Queue pointers accordingly: ITQSP, ITQEP, ITQFP, and
ITQXP.
8. Construct the new TX Group Order Table (includes the added/new link).
9. Point to new TX Group Order Table in the corresponding IMA Group Transmit
Table Entry (IGTTE): TGRPORDER = New Table Offset.
10. Configure this link/PHY as an IMA link in the IMA Root Table by setting the
corresponding bit in IMAPHY. See Table 34-3.
11. Enable the corresponding link/PHY in the IMA Root Table by setting the
corresponding bit in TXPHYEN. See Table 34-3.
12. Software must now wait for the corresponding FE link to go to "active" state (See
Section 34.4.4.1.4, "ICP Cell Templates."). At this point, the link can be configured
to "active mode", capable of sending data cells. Prior to this point, only filler and
ICP cells were transmitted. ILTCNTL[TXSC] = 1.
13. Increment the number of links currently in the group (IGTTE):
TNUMLINKS += 1.
34.5.4.5 Link Removal Procedure
Removing a link from an existing group requires changes to both the group and link table
entries. Aside from the normal exchange of ICP cells by the state machines at the FE and
NE, the following steps should be followed. In general, a link entry is removed from the
existing list of link table entries and the required parameters initialized. Note that if only
one link is used in a group the software must monitor the TC layer in order to detect that
this link has stalled.
34.5.4.5.1 Rx Steps
1. Formulate new group order table with the "dropped" link excluded (see
Section 34.4.4.2.4, "Receive Group Order Tables").
2. The "Stall Threshold" needs to be recalculated. This parameter defines the
acceptable tolerance to an emptied DCB condition (stalled link; see LS exception).
The recommended new value is: STALL_THR = 2 x RNUMLINKS x (3 +
RX_FIFO). See section "IMA Group Receive Table Entry":
IGRTE[STALL_THR] = x.
3. Inhibit storing of cells in DCB for "dropped" link (in IMA Root Table):
REF_LINK &= ~x (i.e., clear the corresponding link bit in the REF_LINK entry).
4. Indicate that the link should be dropped: ILRCNTL[RXSC] = 2.
34-66
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