Freescale Semiconductor MPC8260 - Manual (Page 891)

Multi-Channel Controllers (MCCs)
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
Freescale Semiconductor 28-43
28.8.1.4 Global Overrun (GOV)
An MCC receiver global overrun (GOV) is the receive version of the transmit GUN. Due to different
prioritization and implementation of MCC RX, the likelihood of a GOV occurring is less than a the
likelihood of a GUN. Despite this, all possible causes and recovery procedures apply.
28.9 MCC Buffer Descriptors
Each MCC channel requires two BD tables (one for transmit and one for receive). Each BD contains key
information about the buffer it defines. The BDs are accessed by the MCC as needed; BDs can be added
dynamically to the BDs chain. The RxBDs chain must include at least two BDs; the TxBD chain must
include at least one BDs.
The MCC BDs are located in the external memory.
28.9.1 Receive Buffer Descriptor (RxBD)
Figure 28-21 shows the RxBD.
RxBD fields are described in Table 28-22 .
Table 28-21. GUN Error Recovery—.29
µm (HiP3) Rev B.3 and Subsequent Silicon
Step Action
1 Disable the TDM by clearing the appropriate enable bit in SIxGMR[4-7].
2 Issue the MCC RESET command.
3 Issue the INIT RX AND TX command to cover the channels in use.
4 Reprogram the specific MCC channel, global parameters, and any BDs that need to be updated.
5 Enable TDM by setting appropriate bit.
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Offset + 0 E — W I L F CM — UB — LG NO AB CR SF
1
1
SS7 mode only. Otherwise, reserved.
—
Offset + 2 Data Length
Offset + 4 Rx Data Buffer Pointer
Offset + 6
Figure 28-21. MCC Receive Buffer Descriptor (RxBD)