Current head gives this when I plug a 'Mass Storage Device' into a 2.0 hub:

[  842.760400] hub 1-0:1.0: unable to enumerate USB device on port 3
[  843.080058] usb 1-3: new high-speed USB device number 48 using ehci-pci
[  858.230072] usb 1-3: device descriptor read/64, error -110
[  873.490070] usb 1-3: device descriptor read/64, error -110

Reverting the following commit makes it work again:

commit 55bcdce8a8228223ec4d17d8ded8134ed265d2c5
Author: Alan Stern <stern@rowland.harvard.edu>
Date:   Fri Jan 25 16:52:45 2013 -0500

    USB: EHCI: remove ASS/PSS polling timeout
    
    This patch (as1647) attempts to work around a problem that seems to
    affect some nVidia EHCI controllers.  They sometimes take a very long
    time to turn off their async or periodic schedules.  I don't know if
    this is a result of other problems, but in any case it seems wise not
    to depend on schedule enables or disables taking effect in any
    specific length of time.
    
    The patch removes the existing 20-ms timeout for enabling and
    disabling the schedules.  The driver will now continue to poll the
    schedule state at 1-ms intervals until the controller finally decides
    to obey the most recent command issued by the driver.  Just in case
    this hides a problem, a debugging message will be logged if the
    controller takes longer than 20 polls.
    
    I don't know if this will actually fix anything, but it can't hurt.
    
    Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
    Tested-by: Piergiorgio Sartor <piergiorgio.sartor@nexgo.de>
    CC: <stable@vger.kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/ehci-timer.c b/drivers/usb/host/ehci-timer.c
index 20dbdcb..f904071 100644
--- a/drivers/usb/host/ehci-timer.c
+++ b/drivers/usb/host/ehci-timer.c
@@ -113,14 +113,15 @@ static void ehci_poll_ASS(struct ehci_hcd *ehci)
 
        if (want != actual) {
 
-               /* Poll again later, but give up after about 20 ms */
-               if (ehci->ASS_poll_count++ < 20) {
-                       ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true);
-                       return;
-               }
-               ehci_dbg(ehci, "Waited too long for the async schedule status (%x/%x), giving up\n",
-                               want, actual);
+               /* Poll again later */
+               ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true);
+               ++ehci->ASS_poll_count;
+               return;
        }
+
+       if (ehci->PSS_poll_count > 20)
+               ehci_dbg(ehci, "PSS poll count reached %d\n",
+                               ehci->PSS_poll_count);
        ehci->PSS_poll_count = 0;
 
        /* The status is up-to-date; restart or stop the schedule as needed */

Please note, that I'm using the 'irqpoll' cmdline to improve system stability.