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iio: ad9523-1: Improve reported VCO frequency accuracy 

To improve the accuracy of the reported VCO frequency perform all
multiplications before divisions. This reduces rounding errors and makes
sure the reported rates are accurate down to the last digit.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Lars-Peter Clausen 2019-05-17 16:37:11 +03:00 committed by Jonathan Cameron
parent a2d2010d95
commit 0d698a538f
1 changed files with 5 additions and 3 deletions
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8
drivers/iio/frequency/ad9523.c
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@ -862,9 +862,11 @@ static int ad9523_setup(struct iio_dev *indio_dev)
if (ret < 0)
return ret;
st->vco_freq = (pdata->vcxo_freq * (pdata->pll2_freq_doubler_en ? 2 : 1)
/ pdata->pll2_r2_div) * AD9523_PLL2_FB_NDIV(pdata->
pll2_ndiv_a_cnt, pdata->pll2_ndiv_b_cnt);
st->vco_freq = div_u64((unsigned long long)pdata->vcxo_freq *
(pdata->pll2_freq_doubler_en ? 2 : 1) *
AD9523_PLL2_FB_NDIV(pdata->pll2_ndiv_a_cnt,
pdata->pll2_ndiv_b_cnt),
pdata->pll2_r2_div);
ret = ad9523_write(indio_dev, AD9523_PLL2_VCO_CTRL,
AD9523_PLL2_VCO_CALIBRATE);