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iio: trigger: stm32-timer: fix quadrature mode get routine 

Fixes: 4adec7da05 ("iio: stm32 trigger: Add quadrature encoder device")

SMS bitfiled is mode + 1. After reset, upon boot, SMS = 0. When reading
from sysfs, stm32_get_quadrature_mode() returns -1 (e.g. -EPERM) which is
wrong error code here. So, check SMS bitfiled matches valid encoder mode,
or return -EINVAL.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Acked-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Fabrice Gasnier 2017-07-27 18:18:57 +02:00 committed by Jonathan Cameron
parent eb92b4183d
commit 50b39608ef
1 changed files with 5 additions and 2 deletions
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7
drivers/iio/trigger/stm32-timer-trigger.c
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@ -571,11 +571,14 @@ static int stm32_get_quadrature_mode(struct iio_dev *indio_dev,
{
struct stm32_timer_trigger *priv = iio_priv(indio_dev);
u32 smcr;
int mode;
regmap_read(priv->regmap, TIM_SMCR, &smcr);
smcr &= TIM_SMCR_SMS;
mode = (smcr & TIM_SMCR_SMS) - 1;
if ((mode < 0) || (mode > ARRAY_SIZE(stm32_quadrature_modes)))
return -EINVAL;
return smcr - 1;
return mode;
}
static const struct iio_enum stm32_quadrature_mode_enum = {