My recent Intel box is spewing these messages: xhci_hcd 0000:00:14.0: xHCI Host Controller xhci_hcd 0000:00:14.0: new USB bus registered, assigned bus number 2 usb usb2: New USB device found, idVendor=1d6b, idProduct=0003 usb usb2: New USB device strings: Mfr=3, Product=2, SerialNumber=1 usb usb2: Product: xHCI Host Controller usb usb2: Manufacturer: Linux 4.3.0+ xhci-hcd usb usb2: SerialNumber: 0000:00:14.0 hub 2-0:1.0: USB hub found hub 2-0:1.0: 6 ports detected usb: failed to peer usb2-port2 and usb1-port1 by location (usb2-port2:none) (usb1-port1:usb2-port1) usb usb2-port2: failed to peer to usb1-port1 (-16) usb: port power management may be unreliable usb: failed to peer usb2-port3 and usb1-port1 by location (usb2-port3:none) (usb1-port1:usb2-port1) usb usb2-port3: failed to peer to usb1-port1 (-16) usb: failed to peer usb2-port5 and usb1-port1 by location (usb2-port5:none) (usb1-port1:usb2-port1) usb usb2-port5: failed to peer to usb1-port1 (-16) usb: failed to peer usb2-port6 and usb1-port1 by location (usb2-port6:none) (usb1-port1:usb2-port1) usb usb2-port6: failed to peer to usb1-port1 (-16) Diving into the acpi tables, I noticed the EHCI hub has 12 ports while the XHCI hub has 8 ports. Most of those ports are of connect type USB_PORT_NOT_USED (including port 1 of the EHCI hub). Further the unused ports have location data initialized to 0x80000000. Now each unused port on the xhci hub walks the port list and finds a matching peer with port1 of the EHCI hub because the zero'd out group id bits falsely match. After port1 of the XHCI hub, each following matching peer will generate the above warning. These warnings seem to be harmless for this scenario as I don't think it matters that unused ports could not create a peer link. The attached patch utilizes that assumption and just skips the find_and_link_peer setup if a port is determined to be unused. This further assumes that port's status will never change. Tested on my Intel box. Signed-off-by: Don Zickus <dzickus@xxxxxxxxxx> --- drivers/usb/core/port.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c index 2106183..3a8f84a 100644 --- a/drivers/usb/core/port.c +++ b/drivers/usb/core/port.c @@ -353,6 +353,13 @@ static void find_and_link_peer(struct usb_hub *hub, int port1) struct usb_hub *peer_hub; /* + * Un-used ports have zero'd out data that can create a false + * peer in-use failure. + */ + if (port_dev->connect_type == USB_PORT_NOT_USED) + return; + + /* * If location data is available then we can only peer this port * by a location match, not the default peer (lest we create a * situation where we need to go back and undo a default peering -- 2.6.0.rc0.2.g7662973 -- 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
