On Tue, Oct 29, 2024 at 04:18:50PM -0500, David Lechner wrote: > Replace the call to pwm_get_state() with a call to pwm_get_state_hw() in > the ad7606 driver. This allows reading the sampling_frequency attribute > to return the rate the hardware is actually running at rather than the > rate that was requested. These may differ when the hardware isn't > capable of running at exactly the requested frequency. > > Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx> > --- > > I went ahead and made this patch since it is trivial, but it would be > nice to get a Tested-by from Guillaume to make sure it actually works > as expected. > --- > drivers/iio/adc/ad7606.c | 8 +++----- > 1 file changed, 3 insertions(+), 5 deletions(-) > > diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c > index 8b2046baaa3e..1581eb31b8f9 100644 > --- a/drivers/iio/adc/ad7606.c > +++ b/drivers/iio/adc/ad7606.c > @@ -762,11 +762,9 @@ static int ad7606_read_raw(struct iio_dev *indio_dev, > *val = st->oversampling; > return IIO_VAL_INT; > case IIO_CHAN_INFO_SAMP_FREQ: > - /* > - * TODO: return the real frequency intead of the requested one once > - * pwm_get_state_hw comes upstream. > - */ > - pwm_get_state(st->cnvst_pwm, &cnvst_pwm_state); > + ret = pwm_get_state_hw(st->cnvst_pwm, &cnvst_pwm_state); > + if (ret < 0) > + return ret; > *val = DIV_ROUND_CLOSEST_ULL(NSEC_PER_SEC, cnvst_pwm_state.period); > return IIO_VAL_INT; > } Acked-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxx> There is a slight inconsistency compared to ad7606_set_sampling_freq(): ad7606_set_sampling_freq uses cnvst_pwm_state.period = DIV_ROUND_UP_ULL(NSEC_PER_SEC, freq); . So if cnvst_pwm_state.period happens to be 3 ns then reading the freq value yields 333333333, but if you feed freq=333333333 into ad7606_set_sampling_freq() it sets period = 4. To fix that you'd better use a plain / here in ad7606_read_raw(). (Note that with using round-closest for both there are still corner cases, e.g. period = 31796 ns yields freq = 31450.496917851302 but setting freq = 31450 yields 31796.50238473768 and so 31797.) Best regards Uwe
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