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    Subject[patch 2/3] USB: xhci: Set change bit when warm reset change is set.
    Sometimes, when a USB 3.0 device is disconnected, the Intel Panther Point
    xHCI host controller will report a link state change with the state set
    to "SS.Inactive". This causes the xHCI host controller to issue a warm
    port reset, which doesn't finish before the USB core times out while
    waiting for it to complete.

    When the warm port reset does complete, and the xHC gives back a port
    status change event, the xHCI driver kicks khubd. However, it fails to
    set the bit indicating there is a change event for that port because the
    logic in xhci-hub.c doesn't check for the warm port reset bit.

    After that, the warm port status change bit is never cleared by the USB
    core, and the xHC stops reporting port status change bits. (The xHCI spec
    says it shouldn't report more port events until all change bits are
    cleared.) This means any port changes when a new device is connected will
    never be reported, and the port will seem "dead" until the xHCI driver is
    unloaded and reloaded, or the computer is rebooted. Fix this by making
    the xHCI driver set the port change bit when a warm port reset change bit
    is set.

    A better solution would be to make the USB core handle warm port reset in
    differently, merging the current code with the standard port reset code
    that does an incremental backoff on the timeout, and tries to complete the
    port reset two more times before giving up. That more complicated fix
    will be merged next window, and this fix will be backported to stable.

    This should be backported to kernels as old as 3.0, since that was the
    first kernel with commit a11496ebf37534177d67222285e8debed7a39788
    "xHCI: warm reset support".

    Signed-off-by: Sarah Sharp <>
    Signed-off-by: Greg Kroah-Hartman <>

    drivers/usb/host/xhci-hub.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/drivers/usb/host/xhci-hub.c
    +++ b/drivers/usb/host/xhci-hub.c
    @@ -761,7 +761,7 @@ int xhci_hub_status_data(struct usb_hcd
    memset(buf, 0, retval);
    status = 0;


    spin_lock_irqsave(&xhci->lock, flags);
    /* For each port, did anything change? If so, set that bit in buf. */

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      Last update: 2011-09-20 01:13    [W:0.020 / U:4.120 seconds]
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