Patch "xhci: fix 20000ms port resume timeout" has been added to the 3.18-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    xhci: fix 20000ms port resume timeout

to the 3.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     xhci-fix-20000ms-port-resume-timeout.patch
and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From a54408d0a004757789863d74e29c2297edae0b4d Mon Sep 17 00:00:00 2001
From: Mathias Nyman <mathias.nyman@linux.intel.com>
Date: Thu, 20 Jul 2017 14:48:29 +0300
Subject: xhci: fix 20000ms port resume timeout

From: Mathias Nyman <mathias.nyman@linux.intel.com>

commit a54408d0a004757789863d74e29c2297edae0b4d upstream.

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.

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

---
 drivers/usb/host/xhci-hub.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -651,6 +651,9 @@ static u32 xhci_get_port_status(struct u
 			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);
 


Patches currently in stable-queue which might be from mathias.nyman@linux.intel.com are

queue-3.18/xhci-fix-null-pointer-dereference-when-cleaning-up-streams-for-removed-host.patch
queue-3.18/xhci-fix-20000ms-port-resume-timeout.patch