Released
Datasheet
PM73487 QRT
PMC-Sierra, Inc.
PMC-980618
Issue 3
622 Mbps ATM Traffic Management Device
7.2.22 RX_DIR_CONFIG
The RX_DIR_EXP_ECONG_QD bit in this register sets the congestion threshold for the receive
direction. When the number of free cell buffers falls below this threshold, the configured conges-
tion management actions are taken. A low number sets this threshold to a high number of used
cell buffers.
Address: 1F0000h (7C0000h byte)
Type: Read/Write
Format: Refer to the following table.
Field (Bits)
Description
Not used
(31:16)
Write with a 0 to maintain software compatibility with future versions.
Reserved
(15:12)
Write with a 3h .
RX_DIR_EXP_ECONG_QD
(11:8)
Exponent of the congested queue depth (this is, the number of empty cell buffers below
which the device will enter the empty congestion state). Initialize to the proper setting.
The congestion state is entered when the number of free buffers drops below this thresh-
old, and the congestion state is exited when the number of free buffers exceeds twice
this threshold.
Not used
(7:0)
Write with a 0 to maintain software compatibility with future versions.
7.2.23 RX_DIR_STATE (Internal Structure)
Address: 1F0001h (7C0004h byte)
Type: Read/Write – Write only during SW_RESET (refer to “SW_RESET” on
page 101). Do not update this register.
Format: Refer to the following table.
Field (Bits)
Description
Not used
(31:18)
Write with a 0 to maintain software compatibility with future versions.
Reserved
(17)
Initialize to 0 at initial setup. Software modifications to this location after setup may
cause incorrect operation.
RX_DIR_CONG_STATE
(16)
Congestion state. Initialize to 0.
RX_DIR_E_CUR_QD
(15:0)
Current count of empty cells in the receive direction. Initialize to the number of cells
setting.
NOTE: The number of buffers is limited to the physical number of buffers minus
three.
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PMC [ PMC-SIERRA, INC ]
