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IDT Switch Partitions
Notes
PES48H12G2 User Manual
INTx Interrupt Signaling
Adding an upstream port to a partition causes the upstream port to adopt the aggregated interrupt state
of the downstream ports associated with the destination partition. This may result in the generation of
Assert_INTx and Deassert_INTx messages if the new aggregated state is different from that previously
reported to the root. Adding a downstream port to a partition causes the partition's upstream port to aggre-
gate the interrupt state of the added downstream port. This may result in the generation of Assert_INTx and
Deassert_INTx messages if the new aggregated state is different from that previously reported to the root.
Mode Change Effect on Port
A port mode change triggers the execution of the operation dictated by the OMA field value described in
section No Action Mode Change Behavior on page 6-14 through section Hot Reset Mode Change Behavior
on page 6-15. The following operations are common to all port mode changes.
Buffering
TLPs associated with the port remain queued in the ingress buffers, replay buffers, and egress buffers.
PME Synchronization
Any PME synchronization state associated with the port is reset. If the port has completed PME
synchronization, then the LTSSM transitions to the Detect state and then to the LTSSM state, if any, speci-
fied by the OMA field value.
Bus Locking
Any bus locking state associated with the port is reset.
Port state or context
Any port state or context associated with the previous mode of operation (e.g., downstream switch port)
that is not relevant to the new mode of operation (e.g., upstream switch port) is cleared. All other state is
preserved.
No Action Mode Change Behavior
Modifying the operating mode of a port when the OMA field is set to no action has the following behavior
in addition to that specified by the common operating mode change behavior. The state of all registers
associated with the port are preserved (i.e., they are not reset). Status fields may change as appropriate.
If the link is up, it remains up in operating in the same LTSSM mode (i.e., upstream or downstream). If
the link is down and the new operating mode is an operational mode, then the link begins link training from
the Detect state in the specified LTSSM mode (i.e., upstream or downstream).
Reset Mode Change Behavior
Modifying the operating mode of a port when the OMA field is set to port reset has the following behavior
in addition to that specified by the common operating mode change behavior.
– All state associated with the port is reset. Registers associated with the port are reset to their initial
value except those designated SWSticky. SWSticky register and field contents are preserved.
– The port reset output is asserted (i.e., PxRSTN and/or the corresponding HPxRSTN signal if
mapped to that port).
– The port remains in a reset state for 250 µS (i.e., two times T
asserted while in the reset state. During this time the LTSSM remains in the Detect state.
– The port reset output is negated (i.e., PxRSTN and/or the corresponding HPxRSTN signal if
mapped to that port).
– Following an exit from the reset state, if the new operating mode is an operational mode, then the
link begins link training from the Detect state in the specified LTSSM mode (i.e., upstream or
downstream).
6 - 14
). The port reset output remains
PERST
April 5, 2013
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