Commit ee19ac34 authored by Nikita Yushchenko's avatar Nikita Yushchenko Committed by Jonathan Cameron
Browse files

iio: hi8435: avoid garbage event at first enable 



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: default avatarNikita Yushchenko <nikita.yoush@cogentembedded.com>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent fa7662e1

drivers/iio/adc/hi8435.c

+13 −2
Original line number Diff line number Diff line
@@ -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;

}