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IDT Switch Partitions
Notes
PES48H12G2 User Manual
– The operating mode of a port in upstream switch port mode can't be later modified to downstream
switch port mode, except after a switch fundamental reset. This restriction holds even if the modi-
fication from upstream switch port mode to downstream switch port mode goes through interme-
diate states (e.g., unattached, disabled).
– Similarly, the operating mode of a port in downstream switch port mode can't be later modified to
upstream switch port mode, except after a switch fundamental reset. This restriction holds even if
the modification from downstream switch port mode to upstream switch port mode goes through
intermediate states (e.g., unattached, disabled).
– If a port is attached to a partition, the operating mode of a port must not be modified at the same
time that the state of the partition is being changed.
– If a port is being added to a partition, this action must not be done at the same time that the state
of the partition is being changed.
– Changing the operating mode of a port from unattached to upstream switch port mode requires
that the PCI Express capabilities list and PCI Express extended capabilities list in the port's PCI-
to-PCI bridge function be configured to match the functionality of an upstream port (see section
Capability Structures on page 15-3 for details). Specifically, the following register fields must be
set appropriately.
• NXTPTR field in the PCI Power Management Capabilities (PMCAP) register
• NXTPTR field in the PCI Express VC Extended Capability Header (PCIEVCCAP) register
– The OMA field must be set to 'reset' or 'no action' for the following operating mode changes. If set
to 'no action', it is required that the link be fully retrained by setting the FLRET bit in the port's
PHYLSTATE0 register after the operating mode change completes.
• Unattached port Downstream Switch Port
• Downstream Switch port Unattached port
– If a partition is experiencing a partition fundamental reset initiated by the assertion of the partition's
PARTxPERSTN signal, a port outside the partition can only be added into the partition if the OMA
field is set to 'no action'.
– If a partition is experiencing a partition hot reset initiated by the reception of TS1 ordered-sets on
the partition's upstream port indicating a hot reset, or by the data link layer of the partition's
upstream port transitioning to the DL_Down state, a port outside the partition can only be added
into the partition if the OMA field is set to 'no action'.
Common Operating Mode Change Behavior
This section specifies common port operating mode change behavior that occurs regardless of the OMA
field setting. The following sections describe specific behaviors associated with specific OMA field settings.
Modifying the operating mode of a port requires that no TLP traffic flow through the port during modifica-
tion of the operating mode (i.e., traffic on that port should be quiesced).A port operating mode change may
result in a port being removed from a partition, a port being added to a partition, both a removal and an
addition, or neither.
– The partition from which a port is removed is referred to as the source partition.
– The partition to which a port is added is referred to as the destination partition.
– When a port operating mode changes within a partition, it may have a substantial effect on the
partition and is thus logically viewed as a removal followed by an addition of the same port to the
same partition.
A port operating mode change that is caused only by a device number change is logically viewed as a
source partition removal, followed by a device number change, followed by a destination partition addition
to the same partition. The intent of this requirement is to make a device number change operate in the
same manner as all other port operating mode changes.
6 - 9
April 5, 2013
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