iio: dac: stm32-dac: better handle reset controller failures

Use devm_reset_control_get_optional_exclusive() instead of
devm_reset_control_get_exclusive() as reset controller is optional.

Nevertheless if reset controller is expected but reports an
error, propagate the error code to the caller. In such case
a nice error trace is emitted unless we're deferring the probe
operation.

Signed-off-by: Etienne Carriere <etienne.carriere@st.com>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/dac/stm32-dac-core.c b/drivers/iio/dac/stm32-dac-core.c
index 4d93446..7e5809b 100644 (file)
--- a/drivers/iio/dac/stm32-dac-core.c
+++ b/drivers/iio/dac/stm32-dac-core.c
@@ -147,8 +147,16 @@ static int stm32_dac_probe(struct platform_device *pdev)
        priv->common.vref_mv = ret / 1000;
        dev_dbg(dev, "vref+=%dmV\n", priv->common.vref_mv);
 
-       rst = devm_reset_control_get_exclusive(dev, NULL);
-       if (!IS_ERR(rst)) {
+       rst = devm_reset_control_get_optional_exclusive(dev, NULL);
+       if (rst) {
+               if (IS_ERR(rst)) {
+                       ret = PTR_ERR(rst);
+                       if (ret != -EPROBE_DEFER)
+                               dev_err(dev, "reset get failed, %d\n", ret);
+
+                       goto err_hw_stop;
+               }
+
                reset_control_assert(rst);
                udelay(2);
                reset_control_deassert(rst);