On Thu, 9 Jun 2022 11:32:00 +0300 Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx> wrote: > When buffers are enabled conversion may start asynchronously thus > allowing changes on actual hardware could lead to bad behavior. Thus > do not allow changing oversampling ratio and sample frequency when > buffers are enabled. Less than desirable behavior perhaps, but broken? I don't see this as a fix from what you have mentioned - though I'm not against it. (just drop the fixes tag) It is an ABI change, but unlikely to be one any sane code hits. > > Fixes: 5e1a1da0f8c9 ("iio: adc: at91-sama5d2_adc: add hw trigger and buffer support") > Signed-off-by: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx> > --- > drivers/iio/adc/at91-sama5d2_adc.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c > index a672a520cdc0..b76328da0cb2 100644 > --- a/drivers/iio/adc/at91-sama5d2_adc.c > +++ b/drivers/iio/adc/at91-sama5d2_adc.c > @@ -1644,6 +1644,9 @@ static int at91_adc_write_raw(struct iio_dev *indio_dev, > { > struct at91_adc_state *st = iio_priv(indio_dev); > > + if (iio_buffer_enabled(indio_dev)) > + return -EBUSY; This is racy as nothing stops buffers being enabled after this point. Use the iio_device_claim_direct_mode() and release for this as they protect against the race. > + > switch (mask) { > case IIO_CHAN_INFO_OVERSAMPLING_RATIO: > if ((val != AT91_OSR_1SAMPLES) && (val != AT91_OSR_4SAMPLES) &&