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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>
This commit is contained in:
Guenter Roeck 2014-03-20 08:12:28 -07:00 committed by Lee Jones
parent 5a78401623
commit 204747c970
1 changed files with 5 additions and 2 deletions
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7
drivers/mfd/kempld-core.c
View File

@ -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);