iio: mma8452: avoid switching to active because of config change (e866853d) · Commits · 戴 / test

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:

Martin Kepplinger <martink@posteo.de> Signed-off-by:

Christoph Muellner <christoph.muellner@theobroma-systems.com> Signed-off-by:

Jonathan Cameron <jic23@kernel.org>

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:

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