On Thu, 23 Apr 2015, Chris Bainbridge wrote: > Hardware: IvyBridge Macbook (Panther Point PCH), 2 external USB3 ports > Verified in kernels: 4.0.0+ (1fc1499), Debian 3.16.4 > > All USB3 devices appear as USB2 high-speed (480mbps) rather than USB3 > super-speed (5000mbps). > > usb1 and usb2 are the XHCI USB3 buses. Actually, usb1 is the xHCI USB-2 bus and usb2 is the xHCI USB-3 bus. > usb3 and usb4 are the EHCI USB2 buses > (the EHCI buses are connected to laptop internal devices, not the external ports). > > # lspci | grep USB > 00:14.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB xHCI Host Controller (rev 04) > 00:1a.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller #2 (rev 04) > 00:1d.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller #1 (rev 04) > > dmesg, may be significant: > "can't derive routing for PCI INT A" > "PCI INT A: no GSI" > > [ 1.089819] xhci_hcd 0000:00:14.0: can't derive routing for PCI INT A > [ 1.089825] xhci_hcd 0000:00:14.0: PCI INT A: no GSI > [ 1.089858] xhci_hcd 0000:00:14.0: xHCI Host Controller > [ 1.089910] xhci_hcd 0000:00:14.0: new USB bus registered, assigned bus number 1 > [ 1.090011] xhci_hcd 0000:00:14.0: hcc params 0x20007181 hci version 0x100 quirks 0x0000b930 > [ 1.090025] xhci_hcd 0000:00:14.0: cache line size of 256 is not supported > [ 1.090151] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002 > [ 1.090156] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1 > [ 1.090162] usb usb1: Product: xHCI Host Controller > [ 1.090165] usb usb1: Manufacturer: Linux 4.0.0+ xhci-hcd > [ 1.090169] usb usb1: SerialNumber: 0000:00:14.0 > [ 1.090291] hub 1-0:1.0: USB hub found > [ 1.090315] hub 1-0:1.0: 4 ports detected > [ 1.090524] xhci_hcd 0000:00:14.0: xHCI Host Controller > [ 1.090561] xhci_hcd 0000:00:14.0: new USB bus registered, assigned bus number 2 > [ 1.090663] usb usb2: New USB device found, idVendor=1d6b, idProduct=0003 > [ 1.090667] usb usb2: New USB device strings: Mfr=3, Product=2, SerialNumber=1 > [ 1.090672] usb usb2: Product: xHCI Host Controller > [ 1.090676] usb usb2: Manufacturer: Linux 4.0.0+ xhci-hcd > [ 1.090679] usb usb2: SerialNumber: 0000:00:14.0 > [ 1.090789] hub 2-0:1.0: USB hub found > [ 1.090808] hub 2-0:1.0: 4 ports detected > > Why is usb1 reported as a 480mbit 2.0 root hub? Because that's what it is. The USB-3 spec says that a USB cable contains _two_ independent sets of signalling wires: a backwards-compatible D+/D- pair for USB-2 connections and TX/RX pairs for USB-3 connections. These are represented in the operating system as two separate buses: a USB-2 bus and a USB-3 bus. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
