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SubjectRe: [PATCH v2 5/9] Staging: iio: accel: adis16201: Add comments about units in read_raw()
On Sat, 17 Mar 2018 01:36:22 +0530
Himanshu Jha <himanshujha199640@gmail.com> wrote:

> Clarify the conversion and formation of resultant data in the
> adis16201_read_raw() with sufficient comments and remove the unnecessary
> comments.
>
> Signed-off-by: Himanshu Jha <himanshujha199640@gmail.com>
It is a little illogical to have comments for all but one of the channels, but
given we don't normally comment them unless they are 'odd', this is fine.

Applied, thanks

Jonathan

> ---
> v2:
> -clarify voltage base conversions.
>
> drivers/staging/iio/accel/adis16201.c | 27 ++++++++++++++++++---------
> 1 file changed, 18 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/staging/iio/accel/adis16201.c b/drivers/staging/iio/accel/adis16201.c
> index 8de3f27..97150ea 100644
> --- a/drivers/staging/iio/accel/adis16201.c
> +++ b/drivers/staging/iio/accel/adis16201.c
> @@ -120,31 +120,43 @@ static int adis16201_read_raw(struct iio_dev *indio_dev,
> switch (chan->type) {
> case IIO_VOLTAGE:
> if (chan->channel == 0) {
> + /* Voltage base units are mV hence 1.22 mV */
> *val = 1;
> - *val2 = 220000; /* 1.22 mV */
> + *val2 = 220000;
> } else {
> + /* Voltage base units are mV hence 0.61 mV */
> *val = 0;
> - *val2 = 610000; /* 0.610 mV */
> + *val2 = 610000;
> }
> return IIO_VAL_INT_PLUS_MICRO;
> case IIO_TEMP:
> - *val = -470; /* 0.47 C */
> + *val = -470;
> *val2 = 0;
> return IIO_VAL_INT_PLUS_MICRO;
> case IIO_ACCEL:
> + /*
> + * IIO base unit for sensitivity of accelerometer
> + * is milli g.
> + * 1 LSB represents 0.244 mg.
> + */
> *val = 0;
> - *val2 = IIO_G_TO_M_S_2(462400); /* 0.4624 mg */
> + *val2 = IIO_G_TO_M_S_2(462400);
> return IIO_VAL_INT_PLUS_NANO;
> case IIO_INCLI:
> *val = 0;
> - *val2 = 100000; /* 0.1 degree */
> + *val2 = 100000;
> return IIO_VAL_INT_PLUS_MICRO;
> default:
> return -EINVAL;
> }
> break;
> case IIO_CHAN_INFO_OFFSET:
> - *val = 25000 / -470 - 1278; /* 25 C = 1278 */
> + /*
> + * The raw ADC value is 1278 when the temperature
> + * is 25 degrees and the scale factor per milli
> + * degree celcius is -470.
> + */
> + *val = 25000 / -470 - 1278;
> return IIO_VAL_INT;
> case IIO_CHAN_INFO_CALIBBIAS:
> switch (chan->type) {
> @@ -252,13 +264,11 @@ static int adis16201_probe(struct spi_device *spi)
> struct adis *st;
> struct iio_dev *indio_dev;
>
> - /* setup the industrialio driver allocated elements */
> indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> if (!indio_dev)
> return -ENOMEM;
>
> st = iio_priv(indio_dev);
> - /* this is only used for removal purposes */
> spi_set_drvdata(spi, indio_dev);
>
> indio_dev->name = spi->dev.driver->name;
> @@ -277,7 +287,6 @@ static int adis16201_probe(struct spi_device *spi)
> if (ret)
> return ret;
>
> - /* Get the device into a sane initial state */
> ret = adis_initial_startup(st);
> if (ret)
> goto error_cleanup_buffer_trigger;

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