[LAU] Unbinding USB devices

[Ralf Mardorf]

On Sun, 19 Feb 2017 19:28:57 +0100, Clemens Ladisch wrote:
>Ralf Mardorf wrote:  
>> If I unbind the ehci device that shares the IRQ with audio cards,
>> still all 10 available USB ports work
>>
>> Could somebody explain what this does mean?    
>
>EHCI controllers handle _only_ high-speed (USB 2.0) connections; full-
>and low-speed connections require a separate controller (OHCI or UHCI).
>You probably have a bunch of those.
>  
>> If I unbound ports on my old mobo, they stopped working.    
>
>Some chipsets have EHCI controllers with a built-in hub that handles
>full-/low-speed connections, so for the OS, all connections end up at
>the EHCI controller.  

That was my first thought, since for the old mobo ohci was shown by
lsmod, but to my surprise it isn't for the new mobo. However, this
doesn't explain why the ports are still working for the new mobo, it
becomes just more unclear.

[rocketmouse at archlinux ~]$ lsmod | grep -i hci
xhci_pci               16384  0
xhci_hcd              192512  1 xhci_pci
ahci                   36864  5
libahci                32768  1 ahci
libata                253952  2 ahci,libahci
ehci_pci               16384  0
ehci_hcd               77824  1 ehci_pci
usbcore               249856  5
usbhid,ehci_hcd,xhci_pci,xhci_hcd,ehci_pci

I wonder if there's a way to see at what speed the USB ports are
working?

If I try to check with an external USB drive, it unfortunately shows
irrelevant SATA speed.

$ sudo smartctl -i /dev/sdc | grep SATA
SATA Version is:  SATA 3.0, 6.0 Gb/s (current: 1.5 Gb/s)

Regards,
Ralf