Motorola PowerQUICC II MPC8280 Series Reference Manual page 1280

IMA Software Interface and Requirements
2. TQO (Transmit Queue Overflow)—Indicates that a transmit queue was not ready to
receive a cell (full). This implies that the offending link (PHY) is requesting cells at
a slower rate relative to the TRL. If the TRL is out of spec, then you will see
multiple links reporting TQOs (because all links in the group will be slower relative
to the TRL). The offending link should be removed (see Section 34.5.4.5, "Link
Removal Procedure"), check the following: PHY, TX Queue depth (depth should
be the same as other queues), TNUMLINKS is equal (not less or greater) than the
number of active links.
34.5.4.10 Receive Event Response Procedures
The following RX events may take place when operating in IMA mode. It is recommended
that all events be handled via an "exception/interrupt service routine" (ISR) as the response
time inherent with interrupt driven events should diminish the negative impact/propagation
of such events:
1. LS (Link Stalled)—The link's DCB has emptied, either because the PHY is no
longer functioning or it is relatively slower than the other links. The offending link
should be removed (see Section 34.5.4.5, "Link Removal Procedure"). Make sure
the DCB start and end pointers are not the same. If only one link is used in a group
the software must monitor the TC layer to detect that this link has stalled. No LS
event is reported in the IMA interrupt queue. To re-start an IMA group properly after
link(s) have recovered, the user must reset all the microcode-managed parameters in
the IMA receive group to zero.
2. DCBO (DCB Overflow)—Indicates that the Delay Compensation Buffer has no
more space. The source of the problem can be varied: 1) the offending PHY is
sending at a faster rate (out of spec.), 2) the propagation delay of one of the other
links in the group is greater than anticipated (need to make DCB larger) or, 3) the
size of the offending link was programmed incorrectly, i.e., smaller (the size of all
DCBs in the group should be the same). The offending link should be removed (see
Section 34.5.4.5, "Link Removal Procedure"). This exception corresponds to the
LODS (Link Out of Delay Synchronization Defect) and should be reported to the
FE (via the ICP cell, RxDefect = LODS) of the problem. The MPC8280 will
continue to report this exception if the condition persists (unless the event is
masked).
3. LDS (Link Delay Synchronized)—Indicates that the new/added link (to an existing
group) has achieved synchronization (link delay). The link is capable of receiving
data at this point, (see Section 34.5.4.4, "Link Addition Procedure").
4. GDS (Group Delay Synchronized)—Group delay synchronized achieved or group
delay synchronized not achieved. In some cases, it is not possible for the GDS to
complete. GDS can not complete if a link experiences problems during the GDS
process - for example losing SYNC state for the IFSM. If this occurs, it is not
possible to determine the links true differential delay with respect to other member
34-70
Freescale Semiconductor, Inc.
MPC8280 PowerQUICC II Family Reference Manual
For More Information On This Product,
Go to: www.freescale.com
MOTOROLA