If the connect status change is set during reset signaling, but the status remains connected just retry port reset. This solves an issue with connecting a 90W HP Thunderbolt 3 dock with a Lenovo Carbon x1 (5th generation) which causes a 30min loop of a high speed device being re-discovererd before usb ports starts working. [...] [ 389.023845] usb 3-1: new high-speed USB device number 55 using xhci_hcd [ 389.491841] usb 3-1: new high-speed USB device number 56 using xhci_hcd [ 389.959928] usb 3-1: new high-speed USB device number 57 using xhci_hcd [...] This is caused by a high speed device that doesn't successfully go to the enabled state after the second port reset. Instead the connection bounces (connected, with connect status change), bailing out completely from enumeration just to restart from scratch. Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1716332 Cc: Stable <stable@xxxxxxxxxxxxxxx> Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> --- drivers/usb/core/hub.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 41eaf0b..3461347 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -2710,13 +2710,13 @@ static int hub_port_wait_reset(struct usb_hub *hub, int port1, if (!(portstatus & USB_PORT_STAT_CONNECTION)) return -ENOTCONN; - /* bomb out completely if the connection bounced. A USB 3.0 - * connection may bounce if multiple warm resets were issued, + /* Retry if connect change is set but status is still connected. + * A USB 3.0 connection may bounce if multiple warm resets were issued, * but the device may have successfully re-connected. Ignore it. */ if (!hub_is_superspeed(hub->hdev) && (portchange & USB_PORT_STAT_C_CONNECTION)) - return -ENOTCONN; + return -EAGAIN; if (!(portstatus & USB_PORT_STAT_ENABLE)) return -EBUSY; @@ -2789,6 +2789,10 @@ static int hub_port_reset(struct usb_hub *hub, int port1, dev_dbg(hub->intfdev, "port_wait_reset: err = %d\n", status); + /* USB2 connection bounced, but remains connected */ + if (status == -EAGAIN) + usb_clear_port_feature(hub->hdev, port1, + USB_PORT_FEAT_C_CONNECTION); } /* Check for disconnect or reset */ -- 2.7.4