Commit 204747c9 authored Mar 20, 2014 by Guenter Roeck Committed by Lee Jones Mar 20, 2014

mfd: kempld-core: Fix potential hang-up during boot



On PXT and COMe-cPC2 boards it is observed that the hardware
mutex is acquired but not being released during initialization.
This can result in a hang-up during boot if the driver is built
into the kernel.

Releasing the mutex twice if it was acquired fixes the problem.
Subsequent request/release cycles work as expected, so the fix is
only needed during initialization.

Cc: <stable@vger.kernel.org>
Reviewed-by: Michael Brunner <michael.brunner@kontron.com>
Tested-by: Michael Brunner <michael.brunner@kontron.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

parent 5a784016

drivers/mfd/kempld-core.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -322,9 +322,12 @@ static int kempld_detect_device(struct kempld_device_data *pld)
		return -ENODEV;
		}

		/* Release hardware mutex if aquired */
		if (!(index_reg & KEMPLD_MUTEX_KEY))
		/* Release hardware mutex if acquired */
		if (!(index_reg & KEMPLD_MUTEX_KEY)) {
		iowrite8(KEMPLD_MUTEX_KEY, pld->io_index);
		/* PXT and COMe-cPC2 boards may require a second release */
		iowrite8(KEMPLD_MUTEX_KEY, pld->io_index);
		}

		mutex_unlock(&pld->lock);