How do you interpret the lsusb output?

Question

i was wondering can anyone tell me what does the lsusb output means? example

dodohjk@dodohjk-PC:~$ lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 002: ID 0c45:62c0 Microdia Sonix USB 2.0 Camera

Bus ### ? device ###? Linux Fundation #.#? root hub?

and also the lsusb -t command?

dodohjk@dodohjk-Compaq-Presario-CQ60-Notebook-PC:~$ lsusb -t
/:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=ohci_hcd/4p, 12M
/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=ohci_hcd/3p, 12M
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci_hcd/4p, 480M
    |__ Port 1: Dev 3, If 0, Class=stor., Driver=usb-storage, 480M
    |__ Port 2: Dev 2, If 0, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
    |__ Port 2: Dev 2, If 1, Class='bInterfaceClass 0x0e not yet handled', Driver=uvcvideo, 480M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci_hcd/3p, 480M

especially curious about Driver= blabla /4p and the last number 12M

thanks

Answer 1

I will only answer some specifics of your question. I started answering more, but it took so long to explain in a good way.

Generally interpreting the output:

Here is the best single source I found for interpreting the output: Interpreting the output of lsusb - Diego Assencio.

Driver= blabla /2p, 3p, 4p, etc.

Note that this text is only there for the nodes in the USB device tree, that have classes either root_hub or hub. It denotes the number of ports that this hub has.

I don't know why this information is printed next to the driver, IMO it belongs next to hub or root_hub, but I guess there is a good reason for that.

12M, 480M, etc.

This is the negotiated speed in Mbits/s. Fx USB 1.0 supports 12Mbit/s and USB 2.0 supports 480Mbit/s. However, when a device is connected, the operating system negotiates a speed with the device. Fx a computer mouse often supports USB 2.0, but still gets the negotiated speed 12Mbit/s.