Messages in this thread | | | Subject | Re: [PATCH 2/4] iio: hi8435: avoid garbage event at first enable | From | Jonathan Cameron <> | Date | Sat, 20 May 2017 17:34:40 +0100 |
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On 19/05/17 15:48, Nikita Yushchenko wrote: > Currently, driver generates events for channels if new reading differs > from previous one. This "previous value" is initialized to zero, which > results into event if value is constant-one. > > Fix that by initializing "previous value" by reading at event enable > time. > > This provides reliable sequence for userspace: > - enable event, > - AFTER THAT read current value, > - AFTER THAT each event will correspond to change. > > Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com> I'm hoping there aren't any userspace apps out there relying on this 'unusual' behaviour. *cross fingers*
Applied to the togreg branch of iio.git and pushed out as testing for the autobuilders to play with it.
Thanks,
Jonathan > --- > drivers/iio/adc/hi8435.c | 15 +++++++++++++-- > 1 file changed, 13 insertions(+), 2 deletions(-) > > diff --git a/drivers/iio/adc/hi8435.c b/drivers/iio/adc/hi8435.c > index cb8e6342eddf..45a92e3e8f2b 100644 > --- a/drivers/iio/adc/hi8435.c > +++ b/drivers/iio/adc/hi8435.c > @@ -141,10 +141,21 @@ static int hi8435_write_event_config(struct iio_dev *idev, > enum iio_event_direction dir, int state) > { > struct hi8435_priv *priv = iio_priv(idev); > + int ret; > + u32 tmp; > + > + if (state) { > + ret = hi8435_readl(priv, HI8435_SO31_0_REG, &tmp); > + if (ret < 0) > + return ret; > + if (tmp & BIT(chan->channel)) > + priv->event_prev_val |= BIT(chan->channel); > + else > + priv->event_prev_val &= ~BIT(chan->channel); > > - priv->event_scan_mask &= ~BIT(chan->channel); > - if (state) > priv->event_scan_mask |= BIT(chan->channel); > + } else > + priv->event_scan_mask &= ~BIT(chan->channel); > > return 0; > } >
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