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: <[email protected]>
Reviewed-by: Michael Brunner <[email protected]>
Tested-by: Michael Brunner <[email protected]>
Signed-off-by: Guenter Roeck <[email protected]>
Signed-off-by: Lee Jones <[email protected]>
This commit is contained in:
Guenter Roeck 2014-03-20 08:12:28 -07:00 • committed by Lee Jones
commit 204747c970

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);