usb: musb: fix oops on musb_gadget_pullup

an 'unhandled fault' is causes when a gadget driver calls
usb_gadget_connect() while the USB cable isn't plugged into
the OTG port.

the fault is caused by an access to MUSB's memory space
while its clock is turned off due to pm_runtime kicking
in.

in order to fix the fault, we enclose musb_gadget_pullup()
with pm_runtime_get_sync() ... pm_runtime_put() calls to
be sure we will always reach that path with clock turned on.

[ balbi@ti.com : simplified commit log; removed few things
	which didn't belong there ]

Cc: stable@kernel.org
Reported-by: Zach Pfeffer <zach.pfeffer@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>

diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c
index b67a062..8c41a2e 100644 (file)
--- a/drivers/usb/musb/musb_gadget.c
+++ b/drivers/usb/musb/musb_gadget.c
@@ -1698,6 +1698,8 @@ static int musb_gadget_pullup(struct usb_gadget *gadget, int is_on)
 
        is_on = !!is_on;
 
+       pm_runtime_get_sync(musb->controller);
+
        /* NOTE: this assumes we are sensing vbus; we'd rather
         * not pullup unless the B-session is active.
         */
@@ -1707,6 +1709,9 @@ static int musb_gadget_pullup(struct usb_gadget *gadget, int is_on)
                musb_pullup(musb, is_on);
        }
        spin_unlock_irqrestore(&musb->lock, flags);
+
+       pm_runtime_put(musb->controller);
+
        return 0;
 }