Currently adis16475 supports a sample rate between 1900 and 2100 Hz. This patch changes the setting of sample rate from hardcoded values to a generic computation based on the internal clock frequency. This is a preparatory patch for adding support for adis1657x family devices which allow sample rates between 3900 and 4100 Hz. Signed-off-by: Ramona Gradinariu <ramona.bolboaca13@xxxxxxxxx> --- changes in v2: - new patch drivers/iio/imu/adis16475.c | 39 +++++++++++++++++++++---------------- 1 file changed, 22 insertions(+), 17 deletions(-) diff --git a/drivers/iio/imu/adis16475.c b/drivers/iio/imu/adis16475.c index ab955efdad92..c589f214259b 100644 --- a/drivers/iio/imu/adis16475.c +++ b/drivers/iio/imu/adis16475.c @@ -310,6 +310,9 @@ static int adis16475_set_freq(struct adis16475 *st, const u32 freq) u16 dec; int ret; u32 sample_rate = st->clk_freq; + /* The optimal sample rate for the supported IMUs is between int_clk - 100 and int_clk + 100. */ + u32 max_sample_rate = st->info->int_clk * 1000 + 100000; + u32 min_sample_rate = st->info->int_clk * 1000 - 100000; if (!freq) return -EINVAL; @@ -317,8 +320,9 @@ static int adis16475_set_freq(struct adis16475 *st, const u32 freq) adis_dev_lock(&st->adis); /* * When using sync scaled mode, the input clock needs to be scaled so that we have - * an IMU sample rate between (optimally) 1900 and 2100. After this, we can use the - * decimation filter to lower the sampling rate in order to get what the user wants. + * an IMU sample rate between (optimally) int_clk - 100 and int_clk + 100. + * After this, we can use the decimation filter to lower the sampling rate in order + * to get what the user wants. * Optimally, the user sample rate is a multiple of both the IMU sample rate and * the input clock. Hence, calculating the sync_scale dynamically gives us better * chances of achieving a perfect/integer value for DEC_RATE. The math here is: @@ -336,23 +340,24 @@ static int adis16475_set_freq(struct adis16475 *st, const u32 freq) * solution. In this case, we get the highest multiple of the input clock * lower than the IMU max sample rate. */ - if (scaled_rate > 2100000) - scaled_rate = 2100000 / st->clk_freq * st->clk_freq; + if (scaled_rate > max_sample_rate) + scaled_rate = max_sample_rate / st->clk_freq * st->clk_freq; else - scaled_rate = 2100000 / scaled_rate * scaled_rate; + scaled_rate = max_sample_rate / scaled_rate * scaled_rate; /* * This is not an hard requirement but it's not advised to run the IMU - * with a sample rate lower than 1900Hz due to possible undersampling - * issues. However, there are users that might really want to take the risk. - * Hence, we provide a module parameter for them. If set, we allow sample - * rates lower than 1.9KHz. By default, we won't allow this and we just roundup - * the rate to the next multiple of the input clock bigger than 1.9KHz. This - * is done like this as in some cases (when DEC_RATE is 0) might give - * us the closest value to the one desired by the user... + * with a sample rate lower than internal clock frequency, due to possible + * undersampling issues. However, there are users that might really want + * to take the risk. Hence, we provide a module parameter for them. If set, + * we allow sample rates lower than internal clock frequency. + * By default, we won't allow this and we just roundup the rate to the next + * multiple of the input clock. This is done like this as in some cases + * (when DEC_RATE is 0) might give us the closest value to the one desired + * by the user... */ - if (scaled_rate < 1900000 && !low_rate_allow) - scaled_rate = roundup(1900000, st->clk_freq); + if (scaled_rate < min_sample_rate && !low_rate_allow) + scaled_rate = roundup(min_sample_rate, st->clk_freq); sync_scale = scaled_rate / st->clk_freq; ret = __adis_write_reg_16(&st->adis, ADIS16475_REG_UP_SCALE, sync_scale); @@ -1359,6 +1364,7 @@ static int adis16475_config_sync_mode(struct adis16475 *st) struct device *dev = &st->adis.spi->dev; const struct adis16475_sync *sync; u32 sync_mode; + u16 max_sample_rate = st->info->int_clk + 100; /* default to internal clk */ st->clk_freq = st->info->int_clk * 1000; @@ -1398,10 +1404,9 @@ static int adis16475_config_sync_mode(struct adis16475 *st) /* * In sync scaled mode, the IMU sample rate is the clk_freq * sync_scale. * Hence, default the IMU sample rate to the highest multiple of the input - * clock lower than the IMU max sample rate. The optimal range is - * 1900-2100 sps... + * clock lower than the IMU max sample rate. */ - up_scale = 2100 / st->clk_freq; + up_scale = max_sample_rate / st->clk_freq; ret = __adis_write_reg_16(&st->adis, ADIS16475_REG_UP_SCALE, -- 2.34.1
