IDT 89HPES64H16G2 User Manual page 90

IDT Switch Partitions
Notes
PES64H16G2 User Manual
described in section Partition Hot Reset on page 5-9. An upstream port whose link transition to the Detect
state (i.e., DL_Down) as a result of the operating mode change may trigger a hot-reset in the destination
partition as described in section Partition Hot Reset on page 5-9.
The addition of a downstream port to a destination partition that has a partition hot reset in progress
does not have an effect on the ongoing hot reset in the destination partition (i.e., the hot-reset operation
continues normally on the other ports in the partition). The added downstream port participates in the
ongoing hot reset after the addition of the port has 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 addition of an upstream port whose SRESET bit in the BCTL register is set has
the effect of initiating a partition upstream secondary bus reset.
The addition of a downstream port to a destination partition that has an upstream secondary bus reset in
progress does not have an effect on the ongoing hot reset in the destination partition (i.e., the hot-reset
operation continues normally on the other ports in the partition). The added downstream port participates in
the ongoing hot reset after the addition of the port has 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 addition of a downstream port whose SRESET bit in the BCTL register is set has
no effect on the destination 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
Adding a port to a partition results in the routing specified by configuration registers associated with that
port being enabled in the destination partition.
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 addition:
– 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.
– Adding a downstream port to a partition causes it to affect the L0s ASPM state of upstream port
in the destination partition.
If the upstream port's transmitter is in L0 and a downstream port whose receiver is in L0s is
added to the partition, then an entry to L0s is initiated on the transmitter of the upstream port
per the rules described in section Active State Power Management on page 7-11.
If the upstream port's transmitter is in L0s and a downstream port whose receiver is in L0 is
added to the partition, then an exit from L0s is initiated on the transmitter of the upstream port.
– Adding a downstream port to a partition causes the added port to be affected by the L0s ASPM
state of the upstream port in the destination partition.
For example, if a downstream port whose transmitter is in L0 is added to a switch partition
whose upstream port receiver is in L0s, then an entry to L0s is initiated on the added port's
transmitter per the rules described in section Active State Power Management on page 7-11.
Also, if a downstream port whose transmitter is in L0s is added to a switch partition whose
upstream port receiver is in L0, then an exit from L0s is initiated on the added port's transmit-
ter.
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