Released
Datasheet
PM73487 QRT
PMC-Sierra, Inc.
PMC-980618
Issue 3
622 Mbps ATM Traffic Management Device
(Continued)
Field (Bits)
Description
TX_VO_EXP_CONG_QD
(11:8)
Exponent of the congested VO queue depth. Initialize to the proper setting. The conges-
tion state is entered when the threshold is exceeded, and the congestion state is exited
when the queue length drops below 50 percent of this threshold. Enables congestion
management when:
TX_VO_CUR_QD > 1 + 2TX_VO_EXP_CONG_QD
A value of 0h causes this VO to be in congestion at all times. A value of 1h may not be
used. A value of Fh causes this VO to enter congestion at a depth of 31744 cells.
Not used
(7:0)
Write with a 0 to maintain software compatibility with future versions.
8.4.1.2 TX_VO_STATE (Internal Structure)
Offset: 20h (80h byte)
Type: Read/Write – Do not write after SW_RESET (refer to “SW_RESET” on
page 101) is deasserted.
Index: 1h
Number of entries: 31
Format: Refer to the following table.
Field (Bits)
Description
TX_VO_CONG_ST
(15)
Congestion state bit for the same SC congestion determination. Initialize to 0. This bit is
read-only while cells are flowing.
TX_VO_CUR_QD
(14:0)
Current VO queue depth. This is the count of the unicast cells queued for this VO. Ini-
tialize to 0000h. This field is maintained by a state machine and is read-only after initial-
ization.
8.4.1.3 TX_VO_CELLS_PRES (Internal Structure)
Offset: 40h (100h byte)
Read/Write – Do not write while SW_RESET (refer to “SW_RESET” on page 101) is
deasserted.
Index: 1h
Number of entries: 31
Format: Refer to the following table.
Field (Bits)
Description
RAM is not present in these bit locations.
Not present
(31:16)
TX_VO_CELLS_PRES(15)
(15)
Cells are present in the transmit SCQ 15 for VO = index.
Initialize to 0.
TX_VO_CELLS_PRES(14)
(14)
Cells are present in transmit SCQ 14 for VO = index.
Initialize to 0.
161
PMC [ PMC-SIERRA, INC ]
