xhci: fix 20000ms port resume timeout

A uncleared PLC (port link change) bit will prevent furuther port event
interrupts for that port. Leaving it uncleared caused get_port_status()
to timeout after 20000ms while waiting to get the final port event
interrupt for resume -> U0 state change.

This is a targeted fix for a specific case where we get a port resume event
racing with xhci resume. The port event interrupt handler notices xHC is
not yet running and bails out early, leaving PLC uncleared.

The whole xhci port resuming needs more attention, but while working on it
it anyways makes sense to always ensure PLC is cleared in get_port_status
before setting a new link state and waiting for its completion.

Cc: <stable@vger.kernel.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 364f6027504354026e9330abafdb95e704c690b7..9ef5f68e32131c6bd969a92cc432eafd7204fe69 100644 (file)
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -904,6 +904,9 @@ static u32 xhci_get_port_status(struct usb_hcd *hcd,
                        clear_bit(wIndex, &bus_state->resuming_ports);
 
                        set_bit(wIndex, &bus_state->rexit_ports);
+
+                       xhci_test_and_clear_bit(xhci, port_array, wIndex,
+                                               PORT_PLC);
                        xhci_set_link_state(xhci, port_array, wIndex,
                                        XDEV_U0);