IDT 89HPES64H16G2 User Manual page 88

IDT Switch Partitions
Notes
PES64H16G2 User Manual
When a port operating mode change is initiated, the operation logically executes in the following order.
1. The OMCI bit in the SWPORTxSTS register is set.
2. The effect on the source partition, if appropriate, takes place (i.e., cleanly remove the port from the
partition).
3. The effect on the destination partition, if appropriate, takes place (i.e., cleanly add the port to the
partition).
4. The effect on the port, if appropriate, takes place (i.e., as dictated by the OMA field).
5. The OMCC bit in the SWPORTxSTS register is set.
Mode Change Effect on Source Partition
A port operating mode change that results in a port being removed from a partition has the following
effect on that partition (i.e., the "source" partition).
– If the port that is removed is the upstream port, then the partition operates without an upstream
port as described in section Partition Configuration on page 6-1.
Partition Hot Reset
See section Partition Hot Reset on page 5-9 for an overview of partition hot resets. The removal of an
upstream port that is initiating a partition hot reset (i.e., as the result of reception of TS1 ordered sets with
the hot reset bit set or DL_Down) has the effect of removing the hot reset condition on the partition. The
removal of a downstream port that is affected by a source partition hot reset has no effect on the source
partition (i.e., the hot-reset operation continues normally on the other ports in the partition).
– The removed downstream port stops participating in partition hot reset(s) after the removal of the
port has been completed.
Partition Upstream Secondary Bus Reset
See section Partition Upstream Secondary Bus Reset on page 5-9 for an overview of partition
secondary bus resets. The removal of an upstream port whose SRESET bit in the BCTL register is set has
the same effect as clearing of the SRESET bit (i.e., the partition secondary bus reset condition is removed).
The removal of a downstream port that is affected by a source partition upstream secondary bus reset has
no effect on the source partition (i.e., the hot-reset operation continues normally on the other ports in the
partition).
– The removed downstream port stops participating in the upstream secondary bus reset after the
removal of the port has been completed.
Partition Downstream Secondary Bus Reset
See section Partition Downstream Secondary Bus Reset on page 5-10 for an overview of partition
secondary bus resets. The removal of a downstream port whose SRESET bit in the BCTL register is set
has no effect on the source partition since other ports in the partition are unaffected by this type of reset
(i.e., the hot-reset is propagated to the endpoint located below the port that is being removed).
Routing
Removing a port from a partition results in the corresponding invalidation of routes to that port.
L0s ASPM
A switch partition exhibits a correlation between the L0s ASPM state of its upstream and downstream
port(s). Refer to section Active State Power Management on page 7-11 and to the PCI Express Base spec-
ification for details.
Downstream port removal:
– A switch partition must initiate an exit from L0s on the transmitter of the upstream port if it detects
an exit from L0s on the receiver of any downstream port.
– Removing a downstream port from a partition removes it from affecting the L0s ASPM state of
upstream port in the source partition.
6 - 10 April 5, 2013