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iio: imu: inv_mpu6050: update LPF bandwidth settings 

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>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Jean-Baptiste Maneyrol 2020-02-06 11:31:04 +01:00 committed by Jonathan Cameron
parent 8abce87d39
commit 9fc89f7965
2 changed files with 21 additions and 19 deletions
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30
drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
View File

@ -707,30 +707,32 @@ error_write_raw_unlock:
/**
* 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;

10
drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
View File

@ -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
};