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>

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 95ca07a..4a3bc5b 100644 (file)
--- 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;