Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 1c500840 authored by Olof Johansson's avatar Olof Johansson Committed by Jonathan Cameron
Browse files

iio: accel: bmc150: reset chip at init time 



In at least one known setup, the chip comes up in a state where reading
the chip ID returns garbage unless it's been reset, due to noise on the
wires during system boot.

All supported chips have the same reset method, and based on the
datasheets they all need 1.3 or 1.8ms to recover after reset. So, do
the conservative thing here and always reset the chip.

Signed-off-by: default avatarOlof Johansson <olof@lixom.net>
Reviewed-by: default avatarSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent 36afb176

drivers/iio/accel/bmc150-accel-core.c

+11 −0
Original line number Diff line number Diff line
@@ -67,6 +67,9 @@ 
#define BMC150_ACCEL_REG_PMU_BW		0x10

#define BMC150_ACCEL_DEF_BW			125



#define BMC150_ACCEL_REG_RESET			0x14

#define BMC150_ACCEL_RESET_VAL			0xB6



#define BMC150_ACCEL_REG_INT_MAP_0		0x19

#define BMC150_ACCEL_INT_MAP_0_BIT_SLOPE	BIT(2)
@@ -1497,6 +1500,14 @@ static int bmc150_accel_chip_init(struct bmc150_accel_data *data) 
	int ret, i;

	unsigned int val;



	/*

	 * Reset chip to get it in a known good state. A delay of 1.8ms after

	 * reset is required according to the data sheets of supported chips.

	 */

	regmap_write(data->regmap, BMC150_ACCEL_REG_RESET,

		     BMC150_ACCEL_RESET_VAL);

	usleep_range(1800, 2500);



	ret = regmap_read(data->regmap, BMC150_ACCEL_REG_CHIP_ID, &val);

	if (ret < 0) {

		dev_err(dev, "Error: Reading chip id\n");