iio: trigger: stm32-timer: preset shouldn't be buffered

Currently, setting preset value (ARR) will update directly 'Auto reload
value' only on 1st write access. But then, ARPE is set. This makes
ARR a shadow register. Preset value should be updated upon each
write request: ensure ARPE is 0. This fixes successive writes to
preset attribute.

Fixes: 4adec7da0536 ("iio: stm32 trigger: Add quadrature encoder device")
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
index a9bc5b603b86fee600ff2cb30e37631a726a22ad..4cec28af3ecfedf5014093c3193f0ae35badad41 100644 (file)
--- a/drivers/iio/trigger/stm32-timer-trigger.c
+++ b/drivers/iio/trigger/stm32-timer-trigger.c
@@ -681,8 +681,9 @@ static ssize_t stm32_count_set_preset(struct iio_dev *indio_dev,
        if (ret)
                return ret;
 
+       /* TIMx_ARR register shouldn't be buffered (ARPE=0) */
+       regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, 0);
        regmap_write(priv->regmap, TIM_ARR, preset);
-       regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
 
        return len;
 }