PCI Express 学习篇_物理层 LTSSM（1）：Recovery 子状态介绍

从L0进入Recovery: 最初的到2.5GT/s的训练完成后，如果支持更高速率就会进入Recovery; 请求速率改变或link宽度的改变（一种为了省功耗,例如x16配置为x1,在L0状态的x1甚至比L0s下的x16更加省功耗，另外一种是目前的速率或link宽度不可靠unreliable）;

进入Recovery的原因有以下几类： 1) 从L1状态退出回到L0,因为L1没有FTS序列不能像L0s一样快速回到L0，所以必须通过Recovery再回到L0；

Reporting and recovery is performed in several steps. First, when a PCI hardware error has resulted in a bus disconnect, that event is reported as soon as possible to all affected device drivers, including multiple instances of a device driver on multi-fu

Reporting and recovery is performed in several steps. First, when a PCI hardware error has resulted in a bus disconnect, that event is reported as soon as possible to all affected device drivers, including multiple instances of a device driver on multi-fu

提供了可选的基本重置，以支持少量 PCI Express 设备，对于这些设备，软重置不足以进行恢复。 如果平台支持 PCI 热插拔，那么可以通过切换插槽电源来执行重置。 平台将 PCI 配置空间恢复到“新鲜电源打开”状态，而不是“最后状态”，这一点很重要。

The "Recovery Count" counts the number of changes from L0 to Recovery. It triggers for example during a change in speed, width, or other possible reasons that usually don't mean a PCIe error occured. The other counters however might indicate

虽然具体的子状态划分可能随着PCIe规范的不同版本有所差异，但通常情况下，Recovery状态包含以下几个关键子状态，它们各自负责不同的功能：