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Subject[PATCH 1/4] iio: trigger: stm32-timer: fix quadrature mode get routine
Date
Fixes: 4adec7da0536 ("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>
---
drivers/iio/trigger/stm32-timer-trigger.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
index d22bc56..6aa73d6 100644
--- a/drivers/iio/trigger/stm32-timer-trigger.c
+++ b/drivers/iio/trigger/stm32-timer-trigger.c
@@ -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 = {
--
1.9.1
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