On Mon, 20 Jan 2020 10:36:20 +0100
Jean-Baptiste Maneyrol <jmaneyrol@xxxxxxxxxxxxxx> wrote:
> As every chip has some little variant in LPF bandwidth values,
> use common values that are working for all chips.
> Simplify the LPF setting function.
>
> Signed-off-by: Jean-Baptiste Maneyrol <jmaneyrol@xxxxxxxxxxxxxx>
hmm. On this one I wonder if the 'fix' title is strictly accurate.
It's certainly a good thing to have, but I'm not sure if we will
want to backport it. If you do, then break it out of this series
as a separate fix and add appropriate fixes tag.
All the other patches I haven't commented on in this series look fine
to me subject to Rob's suggestion of combining the dt ID additions for
the binding doc into one patch.
Thanks,
Jonathan
> ---
> drivers/iio/imu/inv_mpu6050/inv_mpu_core.c | 30 ++++++++++++----------
> drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h | 10 ++++----
> 2 files changed, 21 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
> index 9ecc667debbe..c4db9086775c 100644
> --- a/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
> +++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
> @@ -707,30 +707,32 @@ static int inv_mpu6050_write_raw(struct iio_dev *indio_dev,
> /**
> * inv_mpu6050_set_lpf() - set low pass filer based on fifo rate.
> *
> - * Based on the Nyquist principle, the sampling rate must
> - * exceed twice of the bandwidth of the signal, or there
> - * would be alising. This function basically search for the
> - * correct low pass parameters based on the fifo rate, e.g,
> - * sampling frequency.
> + * Based on the Nyquist principle, the bandwidth of the low
> + * pass filter must not exceed the signal sampling rate divided
> + * by 2, or there would be aliasing.
> + * This function basically search for the correct low pass
> + * parameters based on the fifo rate, e.g, sampling frequency.
> *
> * lpf is set automatically when setting sampling rate to avoid any aliases.
> */
> static int inv_mpu6050_set_lpf(struct inv_mpu6050_state *st, int rate)
> {
> - static const int hz[] = {188, 98, 42, 20, 10, 5};
> + static const int hz[] = {400, 200, 90, 40, 20, 10};
> static const int d[] = {
> - INV_MPU6050_FILTER_188HZ, INV_MPU6050_FILTER_98HZ,
> - INV_MPU6050_FILTER_42HZ, INV_MPU6050_FILTER_20HZ,
> + INV_MPU6050_FILTER_200HZ, INV_MPU6050_FILTER_100HZ,
> + INV_MPU6050_FILTER_45HZ, INV_MPU6050_FILTER_20HZ,
> INV_MPU6050_FILTER_10HZ, INV_MPU6050_FILTER_5HZ
> };
> - int i, h, result;
> + int i, result;
> u8 data;
>
> - h = (rate >> 1);
> - i = 0;
> - while ((h < hz[i]) && (i < ARRAY_SIZE(d) - 1))
> - i++;
> - data = d[i];
> + data = INV_MPU6050_FILTER_5HZ;
> + for (i = 0; i < ARRAY_SIZE(hz); ++i) {
> + if (rate >= hz[i]) {
> + data = d[i];
> + break;
> + }
> + }
> result = inv_mpu6050_set_lpf_regs(st, data);
> if (result)
> return result;
> diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h b/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
> index 7ae614052210..9a81098a8b4d 100644
> --- a/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
> +++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
> @@ -370,14 +370,14 @@ enum inv_mpu6050_scan {
> };
>
> enum inv_mpu6050_filter_e {
> - INV_MPU6050_FILTER_256HZ_NOLPF2 = 0,
> - INV_MPU6050_FILTER_188HZ,
> - INV_MPU6050_FILTER_98HZ,
> - INV_MPU6050_FILTER_42HZ,
> + INV_MPU6050_FILTER_NOLPF2 = 0,
> + INV_MPU6050_FILTER_200HZ,
> + INV_MPU6050_FILTER_100HZ,
> + INV_MPU6050_FILTER_45HZ,
> INV_MPU6050_FILTER_20HZ,
> INV_MPU6050_FILTER_10HZ,
> INV_MPU6050_FILTER_5HZ,
> - INV_MPU6050_FILTER_2100HZ_NOLPF,
> + INV_MPU6050_FILTER_NOLPF,
> NUM_MPU6050_FILTER
> };
>
