[RFC PATCH] iio: ak8975: Make sure chipset is always initialized

[Daniel Baluta <daniel.baluta@intel.com>]

When using ACPI, if acpi_match_device fails then chipset enum will be
uninitialized and &ak_def_array[chipset] will point to some bad address.

This fixes the following compilation warning:

drivers/iio/magnetometer/ak8975.c: In function ‘ak8975_probe’:
drivers/iio/magnetometer/ak8975.c:788:14: warning: ‘chipset’ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  data->def = &ak_def_array[chipset];

Reported-by: Octavian Purdila <octavian.purdila@intel.com>
Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
---
This is a RFC because while I'm pretty sure that chipset should be initialized
with AK_MAX_TYPE in ak8975_match_acpi_device, I am not sure if we can live with
a NULL return value of ak8975_match_acpi_device. Current implementation ignores
return value of ak8975_match_acpi_device.

The same situation is for kxcjk-1013, bmc150-accel, bmg160 and possible other
drivers.

 drivers/iio/magnetometer/ak8975.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
index 0d10a4b..cdf9e77 100644
--- a/drivers/iio/magnetometer/ak8975.c
+++ b/drivers/iio/magnetometer/ak8975.c
@@ -716,6 +716,7 @@ static const char *ak8975_match_acpi_device(struct device *dev,
 {
 	const struct acpi_device_id *id;
 
+	*chipset = AK_MAX_TYPE;
 	id = acpi_match_device(dev->driver->acpi_match_table, dev);
 	if (!id)
 		return NULL;
-- 
1.9.1