EHCI: only power off port if over-current is active

MAX4967 USB power supply chip we use on our boards signals over-current when
power is not enabled; once it's enabled, over-current signal returns to normal.
That unfortunately caused the endless stream of "over-current change on port"
messages. The EHCI root hub code reacts on every over-current signal change
with powering off the port -- such change event is generated the moment the
port power is enabled, so once enabled the power is immediately cut off.
I think we should only cut off power when we're seeing the active over-current
signal, so I'm adding such check to that code. I also think that the fact that
we've cut off the port power should be reflected in the result of GetPortStatus
request immediately, hence I'm adding a PORTSCn register readback after write...

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: stable@kernel.org
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index d9e8d713f485cf5a8d044f3bf24544a2c80d1f43..bf2c8f65e1aefc6c4d89e9dfe15a9f4a804f090e 100644 (file)
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -816,10 +816,11 @@ static int ehci_hub_control (
                         * power switching; they're allowed to just limit the
                         * current.  khubd will turn the power back on.
                         */
-                       if (HCS_PPC (ehci->hcs_params)){
+                       if ((temp & PORT_OC) && HCS_PPC(ehci->hcs_params)) {
                                ehci_writel(ehci,
                                        temp & ~(PORT_RWC_BITS | PORT_POWER),
                                        status_reg);
+                               temp = ehci_readl(ehci, status_reg);
                        }
                }