From ee19ac340c5fdfd89c6348be4563453c61ab54a9 Mon Sep 17 00:00:00 2001 From: Nikita Yushchenko Date: Fri, 19 May 2017 17:48:00 +0300 Subject: [PATCH] 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: Nikita Yushchenko Signed-off-by: Jonathan Cameron --- 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; } -- 2.39.5