EHCI: always clear the STS_FLR status bit

This patch (as1544) fixes a problem affecting some EHCI controllers.
They can generate interrupts whenever the STS_FLR status bit is turned
on, even though that bit is masked out in the Interrupt Enable
register.

Since the driver doesn't use STS_FLR anyway, the patch changes the
interrupt routine to clear that bit whenever it is set, rather than
leaving it alone.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-and-tested-by: Tomoya MORINAGA <tomoya.rohm@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 95ca07a8e1b5..4a3bc5b7a06f 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -858,8 +858,13 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd)
                 goto dead;
         }
 
+        /*
+         * We don't use STS_FLR, but some controllers don't like it to
+         * remain on, so mask it out along with the other status bits.
+         */
+        masked_status = status & (INTR_MASK | STS_FLR);
+
         /* Shared IRQ? */
-        masked_status = status & INTR_MASK;
         if (!masked_status || unlikely(ehci->rh_state == EHCI_RH_HALTED)) {
                 spin_unlock(&ehci->lock);
                 return IRQ_NONE;