4.9-stable review patch. If anyone has any objections, please let me know.
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From: Nikita Yushchenko nikita.yoush@cogentembedded.com
[ 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 --- drivers/iio/adc/hi8435.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-)
--- a/drivers/iio/adc/hi8435.c +++ b/drivers/iio/adc/hi8435.c @@ -121,10 +121,21 @@ static int hi8435_write_event_config(str 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; }