31:16

0h

RO

Reserved

15:8

0h

RO

Effective Granularity (EG)

Root Port does not support PTM Requester role.

7:3

0h

RO

Reserved

2

0b

RW

PTM Propagation Delay Adaptation Interpretation B (PTMPDAIB)

If PTM Propagation Delay Adaptation Capable is Set, then this bit when Set selects interpretation B of the Propagation Delay[31:0] field in the PTM ResponseD Message



For a Switch, if a specific Port is permanently attached such that this control is not required, it is permitted for that Port for this bit to be RsvdP.



Default value is 0b.

1

0b

RW

Root Select (RS)

When Set, if the PTM Enable bit is also Set, this Time Source is the PTM Root. Within each PTM Hierarchy, it is recommended that system software select only the furthest Upstream Time Source to be the PTM Root.

0

0b

RW

PTM Enable (PTME)

When Set, this Function is permitted to participate in the PTM mechanism according to its selected role.
Software must not have the PTM Enable bit Set in the PTM Control register on a Function associated with an Upstream Port unless the associated Downstream Port on the Link already has the PTM Enable bit Set in its associated PTM Control register.