From: Jonathan Cameron <jic23@kernel.org>
To: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>
Cc: linux-iio@vger.kernel.org, devicetree@vger.kernel.org,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH v2 5/6] iio: imu: inv_mpu6050: update LPF bandwidth settings
Date: Thu, 6 Feb 2020 12:16:07 +0000 [thread overview]
Message-ID: <20200206121607.576051dd@archlinux> (raw)
In-Reply-To: <20200206103105.23666-6-jmaneyrol@invensense.com>
On Thu, 6 Feb 2020 11:31:04 +0100
Jean-Baptiste Maneyrol <jmaneyrol@invensense.com> 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@invensense.com>
Applied, thanks
> ---
> 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
> };
>
next prev parent reply other threads:[~2020-02-06 12:16 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-06 10:30 [PATCH v2 0/6] Add support of similar chips Jean-Baptiste Maneyrol
2020-02-06 10:31 ` [PATCH v2 1/6] iio: imu: inv_mpu6050: cleanup of/acpi support Jean-Baptiste Maneyrol
2020-02-06 11:51 ` Jonathan Cameron
2021-11-08 17:52 ` Jonathan Cameron
2020-02-06 10:31 ` [PATCH v2 2/6] iio: imu: inv_mpu6050: add support of ICM20609 & ICM20689 Jean-Baptiste Maneyrol
2020-02-06 11:53 ` Jonathan Cameron
2020-02-06 10:31 ` [PATCH v2 3/6] iio: imu: inv_mpu6050: add support of IAM20680 Jean-Baptiste Maneyrol
2020-02-06 12:09 ` Jonathan Cameron
2020-02-06 10:31 ` [PATCH v2 4/6] iio: imu: inv_mpu6050: add support of ICM20690 Jean-Baptiste Maneyrol
2020-02-06 12:15 ` Jonathan Cameron
2020-02-06 10:31 ` [PATCH v2 5/6] iio: imu: inv_mpu6050: update LPF bandwidth settings Jean-Baptiste Maneyrol
2020-02-06 12:16 ` Jonathan Cameron [this message]
2020-02-06 10:31 ` [PATCH v2 6/6] dt-bindings: add description for new supported chips Jean-Baptiste Maneyrol
2020-02-06 12:16 ` Jonathan Cameron
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