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. PTM support by a Function is indicated by the presence of a PTM Extended Capability structure. It is not required that all Endpoints in a hierarchy support PTM, and it is not required for software to enable PTM in all Endpoints that do support it. If a PTM Message is received by a Port that does not support PTM, or by a Downstream Port when the PTM Enable bit is clear, the Message must be treated as an Unsupported Request. This is a reported error associated with the Receiving Port (see Section 6.2 ). A Properly formed PTM Response received by an Upstream Ports that support PTM, but for which the PTM Enable bit is clear, must be silently discarded.

如果与上行端口相关联的功能的PTM控制寄存器中未设置PTM使能位，则软件不能在其中设置PTM控制寄存器中的PTM使能位，除非链接上的关联下行端口已经在其关联的PTM控制寄存器中设置了PTM使能位。支持PTM的功能通过PTM扩展能力结构的存在进行指示。并不要求层次结构中的所有端点都支持PTM，也不要求在所有支持PTM的端点中启用PTM。如果一个不支持PTM的端口或者当PTM使能位被清除时，一个下行端口接收到了PTM消息，则该消息必须被视为不支持的请求。这是与接收端口相关联的报告错误（参见第6.2节）。对于支持PTM的上行端口而言，如果PTM响应的PTM使能位被清除，则必须默默地丢弃它。

相关问题

• Support for the PTM Responder role is indicated by setting the PTM Responder Capable bit in the PTM Capability register. • Switches and Root Complexes are permitted to implement the PTM Responder Role. ◦ A PTM capable Switch, when enabled for PTM by setting the PTM Enable bit in the PTM Control register associated with the Switch Upstream Port, must respond to all PTM Request Messages received at any of its Downstream Ports. ◦ The mechanism by which Root Complexes communicate PTM Master Time to RCiEPs is implementation specific. 翻译

• 支持 PTM Responder 角色需要在 PTM Capability 寄存器中设置 PTM Responder Capable 位。 • Switches 和 Root Complexes 允许实现 PTM Responder 角色。 ◦ PTM capable Switch，在通过设置与 Switch Upstream Port 相关的 PTM Control 寄存器的 PTM Enable 位启用 PTM 后，必须响应其所有 Downstream Ports 收到的所有 PTM Request Messages。 ◦ Root Complexes 将 PTM Master Time 传递给 RCiEPs 的机制是实现特定的。

In addition to the requirements listed above for the PTM Requester and PTM Responder Roles, Switches must follow these requirements: • When the Upstream Port is associated with a Multi-Function Device, only a single Function associated with that Upstream Port is permitted to implement the PTM Extended Capability structure. For Switches, all PTM functionality associated with the Switch must be controlled through that structure. It is not required that the Function implementing the PTM Extended Capability structure be the Switch Upstream Port Function. • The PTM Extended Capability structure for a Switch must indicate support for both the PTM Requester and PTM Responder roles. • The PTM Extended Capability in the Upstream Port controls all Switches in that Upstream Port. • A Switch is permitted to act as a PTM Root, or to issue PTM Requests on its Upstream Port to obtain the PTM Master Time for use in fulfilling PTM Requests received at its Downstream Ports. In the latter case the Switch must account for any internal delays within the Switch. 翻译

除了 PTM 请求者和 PTM 响应者角色的要求之外，交换机必须遵循以下要求：
• 当上行端口与多功能设备相关联时，只允许与该上行端口相关联的单个功能实现 PTM 扩展能力结构。对于交换机，所有与交换机相关的 PTM 功能必须通过该结构进行控制。实现 PTM 扩展能力结构的功能不必是交换机上行端口功能。
• 交换机的 PTM 扩展能力结构必须指示支持 PTM 请求者和 PTM 响应者角色。
• 上行端口中的 PTM 扩展能力控制该上行端口中的所有交换机。
• 交换机可以作为 PTM 根，或者在其上行端口发出 PTM 请求以获取用于满足其下行端口接收的 PTM 请求的 PTM 主时间。在后一种情况下，交换机必须考虑交换机内部延迟。