Hi Nikita,
On 19.05.2017 17:48, 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@xxxxxxxxxxxxxxxxxx>
---
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);
This will race with hi8435_iio_push_event for priv->event_scan_mask.
Since you adding raw access then it is reasonable to initialize
priv->event_prev_val in hi8435_read_raw.
Then use the following sequence for your application:
1. read raw value
2. enable events
Regards,
Vladimir
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