| Message ID | 20241029-pwm-export-pwm_get_state_hw-v2-2-03ba063a3230@baylibre.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | pwm: export pwm_get_state_hw() | expand |
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@baylibre.com> > --- > > 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@baylibre.com> 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
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; }
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@baylibre.com> --- 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(-)