Re: [PATCH v4 1/1] iio: accell: mma8452: Reduce sleep time when data not ready

[Jonathan Cameron <jic23@kernel.org>]

On Fri, 11 May 2018 16:54:59 +0800
Richard Tresidder <rtresidd@electromag.com.au> wrote:

> Modified the sleep method when data is not ready to allow for sampling > 50sps to work.
> 
> Signed-off-by: Richard Tresidder <rtresidd@electromag.com.au>
Applied to the togreg branch of iio.git and pushed out as testing for the
autobuilders to play with it.

Thanks,

Jonathan

> ---
> 
> Notes:
>     v4: Changes from v3
>       * fix long line
>       * fix eol issues with patch
>     
>     v3: Changes from v2
>       * Removed fallthrough fix (will submit separately)
>       * Fixed some blank lines, trailing white spaces.
>     
>     v2: Changes from v1
>       * Remove whitespace changes
>       * Added fallthrough fix (subsequently removed
> 
>  drivers/iio/accel/mma8452.c | 24 +++++++++++++++++++++++-
>  1 file changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
> index 7a2da7f..7e3d82c 100644
> --- a/drivers/iio/accel/mma8452.c
> +++ b/drivers/iio/accel/mma8452.c
> @@ -106,6 +106,7 @@ struct mma8452_data {
>  	u8 ctrl_reg1;
>  	u8 data_cfg;
>  	const struct mma_chip_info *chip_info;
> +	int sleep_val;
>  };
>  
>   /**
> @@ -193,7 +194,11 @@ static int mma8452_drdy(struct mma8452_data *data)
>  		if ((ret & MMA8452_STATUS_DRDY) == MMA8452_STATUS_DRDY)
>  			return 0;
>  
> -		msleep(20);
> +		if (data->sleep_val <= 20)
> +			usleep_range(data->sleep_val * 250,
> +				     data->sleep_val * 500);
> +		else
> +			msleep(20);
>  	}
>  
>  	dev_err(&data->client->dev, "data not ready\n");
> @@ -544,6 +549,18 @@ static int mma8452_read_raw(struct iio_dev *indio_dev,
>  	return -EINVAL;
>  }
>  
> +static int mma8452_calculate_sleep(struct mma8452_data *data)
> +{
> +	int ret, i = mma8452_get_odr_index(data);
> +
> +	if (mma8452_samp_freq[i][0] > 0)
> +		ret = 1000 / mma8452_samp_freq[i][0];
> +	else
> +		ret = 1000;
> +
> +	return ret == 0 ? 1 : ret;
> +}
> +
>  static int mma8452_standby(struct mma8452_data *data)
>  {
>  	return i2c_smbus_write_byte_data(data->client, MMA8452_CTRL_REG1,
> @@ -700,6 +717,8 @@ static int mma8452_write_raw(struct iio_dev *indio_dev,
>  		data->ctrl_reg1 &= ~MMA8452_CTRL_DR_MASK;
>  		data->ctrl_reg1 |= i << MMA8452_CTRL_DR_SHIFT;
>  
> +		data->sleep_val = mma8452_calculate_sleep(data);
> +
>  		ret = mma8452_change_config(data, MMA8452_CTRL_REG1,
>  					    data->ctrl_reg1);
>  		break;
> @@ -1593,6 +1612,9 @@ static int mma8452_probe(struct i2c_client *client,
>  
>  	data->ctrl_reg1 = MMA8452_CTRL_ACTIVE |
>  			  (MMA8452_CTRL_DR_DEFAULT << MMA8452_CTRL_DR_SHIFT);
> +
> +	data->sleep_val = mma8452_calculate_sleep(data);
> +
>  	ret = i2c_smbus_write_byte_data(client, MMA8452_CTRL_REG1,
>  					data->ctrl_reg1);
>  	if (ret < 0)