USB Hub

1 包含MCU的全速Hub
1.1 数据流
这种类型的Hub主要用来实现Compound设备，需要实现Hub和HID 2个固件模块。也叫键盘USB Hub。
1）低速vs低速：upstream <-> repeater <-> downstream
2）全速vs全速：upstream <-> repeater <-> downstream
3）枚举：upstream <-> SIE <-> Hub Controller（固件实现或者ASIC）

1.2 show case
AT43USB355
CY7C65113C

2 包含MCU的高速Hub
2.1 数据流
1）高速vs高速：upstream <-> repeater <-> downstream
2）高速vs全速/低速：upstream <-> SIE <-> TT <-> downstream
3）枚举：upstream <-> SIE <-> Hub Controller（固件实现或者ASIC）

2.2 show case
Aspeed SoC AST2500 (Aspeed Technology) vhub
drivers/usb/gadget/udc/aspeed-vhub/hub.c

3 Linux USB hub
3.1 DWC USB3
DWC_usb3_databook_2.50a.pdf
In multi-port Host mode, multiple instances of the PHY, Link, and MAC layers are instantiated. Buffer management also has separate Rx and Tx buffers for each bus instance. Refer to page 69.

In host mode, each Bus Instance per speed has its own TxFIFO shared among all OUT endpoints, whereas, in device mode, each IN endpoint has its own separate TxFIFO. Refer to 3.11.
Host TxFIFOs: one per UxMAC, U3MAC, U2MAC, FMAC
Host RxFIFOs: one per UxMAC, U3MAC, U2MAC, FMAC

Two downstream ports with shared bandwidth, refer to opencores OHCI Full/Low-Speed USB Host Controller.

3.2 HUB3CV
USB-IF官网Document Library下载HUB3CV工具。

3.3 libusb库的使用
Read my blog “Android libusb库的使用”。

3.4 CW23WWDD
hub.c中找到USB device number，然后在后面加上CW23WWDD，用来确认版本。

4 Abbreviations
EM：ELAN Microelectronics Corp
HUB3CV：USB 3 Hub Command Verifier Ver. 2.1.12.1
USB BH reset：Bigger Hammer or Brad Hosler，表示warm reset；you may be confused why the USB 3.0 spec calls the same type of reset "warm reset" in some places and "BH reset" in other places. "BH" reset is supposed to stand for "Big Hammer" reset, but it also stands for "Brad Hosler". Brad died shortly after the USB 3.0 bus specification was started, and they decided to name the reset after him. The suggestion was made shortly before the spec was finalized, so the wording is a bit inconsistent.