diff options
| author | Nikita Yushchenko <nikita.yoush@cogentembedded.com> | 2017-05-19 17:48:00 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-04-13 19:48:02 +0200 |
| commit | a1aeeacc646dc2e576512988b7f721751c0373ef (patch) | |
| tree | 1f5b439089cfeeacc29c0577ffd498ef7502abe3 /drivers/iio | |
| parent | 581ec36f26ad69b70ec3ed4ee552bd38b961d917 (diff) | |
iio: hi8435: avoid garbage event at first enable
[ Upstream commit ee19ac340c5fdfd89c6348be4563453c61ab54a9 ]
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>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/iio')
| -rw-r--r-- | drivers/iio/adc/hi8435.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/drivers/iio/adc/hi8435.c b/drivers/iio/adc/hi8435.c index 678e8c7ea763..52b2dcf1d942 100644 --- a/drivers/iio/adc/hi8435.c +++ b/drivers/iio/adc/hi8435.c @@ -121,10 +121,21 @@ 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; } |