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>
diff --git a/drivers/mfd/kempld-core.c b/drivers/mfd/kempld-core.c
index 20a6afc..0769260 100644
--- a/drivers/mfd/kempld-core.c
+++ b/drivers/mfd/kempld-core.c
@@ -322,9 +322,12 @@
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);