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Commit e866853d authored by Martin Kepplinger's avatar Martin Kepplinger Committed by Jonathan Cameron
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iio: mma8452: avoid switching to active because of config change 



The devices' config registers can only be changed in standby mode.
Up until now the driver just held the device *always* active, so for
changing a config it was *always* necessary to switch to standby.

For upcoming support for runtime pm, the device can as well be in standby
mode. Instead of putting runtime pm functions in there, just keep the
device in standby if it already is. This section is protected by a lock
after all.

Signed-off-by: default avatarMartin Kepplinger <martink@posteo.de>
Signed-off-by: default avatarChristoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent 8b8ff3a6

drivers/iio/accel/mma8452.c

+29 −6
Original line number Diff line number Diff line
@@ -393,24 +393,47 @@ static int mma8452_active(struct mma8452_data *data) 
					 data->ctrl_reg1);

}



/* returns >0 if active, 0 if in standby and <0 on error */

static int mma8452_is_active(struct mma8452_data *data)

{

	int reg;



	reg = i2c_smbus_read_byte_data(data->client, MMA8452_CTRL_REG1);

	if (reg < 0)

		return reg;



	return reg & MMA8452_CTRL_ACTIVE;

}



static int mma8452_change_config(struct mma8452_data *data, u8 reg, u8 val)

{

	int ret;

	int is_active;



	mutex_lock(&data->lock);



	is_active = mma8452_is_active(data);

	if (is_active < 0) {

		ret = is_active;

		goto fail;

	}



	/* config can only be changed when in standby */

	if (is_active > 0) {

		ret = mma8452_standby(data);

		if (ret < 0)

			goto fail;

	}



	ret = i2c_smbus_write_byte_data(data->client, reg, val);

	if (ret < 0)

		goto fail;



	if (is_active > 0) {

		ret = mma8452_active(data);

		if (ret < 0)

			goto fail;

	}



	ret = 0;

fail: