T8207 Datasheet, PDF (99/158 Pages) Agere Systems – ATM Interconnect

Advance Data Sheet
September 2001
CelXpres T8207
ATM Interconnect
14 Registers (continued)
Table 59. Main Configuration 2 (MCF2) (0112h) (continued)
Name
T8207_sel
Bit Pos.
4
dont_inhibit_rxphy 5
_clav
inhibit_rxuto_fifo_
6
overrun
Reserved
7:5
div_queue
10:8
Reserved
Reserved
14:11
15
Type
RW
RW
RW
RO
RW
RO
RW
Reset
Description
0 T8207 Select Bit. This bit should be programmed to ‘1’ to obtain all of the
T8207 features. If this bit is programmed to ‘0,’ the two additional div_queue
bit settings (“100” and “101”) affect its operation. If div_queue is pro-
grammed to “100” and the T8207_sel bit is ‘0,’ the TX UTOPIA cell buffer is
divided into 64 queues, but only 32 are used. In addition, if this bit is pro-
grammed to ‘0,’ the UTOPIA Configuration 3 (011Ah) (Table 63), Master
Queue 3 (0158h) (Table 80), Master Queue 2 (015Ah) (Table 81), TX PHY
FIFO Routing 3 (0178h) (Table 86), and TX PHY FIFO Routing 2 (017Ah)
(Table 87) registers do not need to be programmed.
0 Don’t Inhibit RX PHY_CLAV. This bit, when set to ‘1,’ keeps the rx_clav sig-
nal always asserted high, indicating the capability to accept cells even if the
RX UTOPIA FIFO could overrun, or is actually overrun. This bit is valid only
when the RX UTOPIA is in PHY mode.
When this bit is cleared to ‘0,’ the rx_clav signal is deasserted if the RX
UTOPIA FIFO is considered full.
0 Inhibit RX UTOPIA FIFO Overrun. This bit, when set to ‘1,’ prevents the RX
UTOPIA FIFO from overflowing by deasserting its rx_enb* signal, even
though the rx_clav signal is high when polled, if the RX UTOPIA FIFO is
considered full. It is considered full when four cells are stored in it that have
not yet been read and processed by the T8207. This bit is valid when the RX
UTOPIA is in ATM mode.
When this bit is cleared to ‘0,’ the rx_enb* signal is not deasserted even if
the RX UTOPIA FIFO is considered full.
0 Reserved.
0 Divide into Queues. These bits indicate the number of queues used in the
TX UTOPIA cell buffer as follows:
“000” = 4 queues—32 cells per queue
“001” = 8 queues—16 cells per queue
“010” = 16 queues—8 cells per queue
“011” = 32 queues—4 cells per queue
“100” = 64 queues—2 cells per queue
“101” = 1 queue—128 cells per queue
When the T8207 is configured to UTOPIA level 1 ATM mode or when it is
configured for PHY mode, the number of queues selected should be one to
maximize cell buffering.
T8207_sel = 1 (up to 32 PHYs are supported):
When the device is configured to UTOPIA level 2 ATM mode and is con-
nected to multiple PHY ports, each PHY port uses four queues unless 32
PHY ports are selected. If 32 PHY ports are selected, each PHY port uses
two queues. Therefore, for 16 or less PHY ports, selecting four queues will
provide only for PHY port 0, selecting eight queues will provide only for PHY
ports 0 and 1, and so on. For 32 PHY ports, selecting four queues will pro-
vide only for PHY ports 0 and 1, selecting eight queues will provide only for
PHY ports 0, 1, 2, and 3, and so on.
T8207_sel = 0 (up to 16 PHYs are supported):
When the device is configured to UTOPIA level 2 ATM mode and is con-
nected to multiple PHY ports, each PHY port uses four queues unless 16
PHY ports are selected. If 16 PHY ports are selected, each PHY port uses
two queues. Therefore, for 8 or less PHY ports, selecting four queues will
provide only for PHY port 0, selecting eight queues will provide only for PHY
ports 0 and 2, and so on. For 16 PHY ports, selecting four queues will pro-
vide only for PHY ports 0 and 1, selecting eight queues will provide only for
PHY ports 0, 1, 2, and 3, and so on.
0 Reserved.
0 Reserved. Program this bit to ‘1.’
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