hardware - USB和PCI之间的关系

Question

我对 linux 设备驱动程序书中的以下陈述感到有些困惑。
http://www.linuxdriver.co.il/ldd3/

13.2. USB and Sysfs To help understand what this long device path means, we describe how the kernel labels the USB devices. The first USB device is a root hub. This is the USB controller, usually contained in a PCI device. The controller is so named because it controls the whole USB bus connected to it. The controller is a bridge between the PCI bus and the USB bus, as well as being the first USB device on that bus.

尤其是“ Controller 是PCI总线和USB总线之间的桥梁”这句话

是这样吗？我的印象是 PCI 和 USB 都是不同的总线。
请澄清。

Answer 1

它们确实是不同的总线，这就是为什么您需要在它们之间建立一个桥接器，以便 CPU 可以通过 PCI 通过桥接器与 USB 总线上的东西进行通信。

CPU ---(front-side bus)----  PCI controller ----(PCI-bus)-+--   USB controller ----(USB-bus)--+-- USB mouse
                                                          |                                   +--- USB printer
                                                          +--   SATA controller