On 03/03/16 08:24, Martin Kepplinger wrote:
> 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@xxxxxxxxx>
> Signed-off-by: Christoph Muellner <christoph.muellner@xxxxxxxxxxxxxxxxxxxxx>
Applied to the togreg branch of iio.git - initially pushed out as testing
Thanks,
Jonathan
> ---
> drivers/iio/accel/mma8452.c | 35 +++++++++++++++++++++++++++++------
> 1 file changed, 29 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
> index 17d72bc..9c4a84a 100644
> --- a/drivers/iio/accel/mma8452.c
> +++ b/drivers/iio/accel/mma8452.c
> @@ -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);
>
> - /* config can only be changed when in standby */
> - ret = mma8452_standby(data);
> - if (ret < 0)
> + 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;
>
> - ret = mma8452_active(data);
> - 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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