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From:   Fabrice Gasnier <fabrice.gasnier@st.com>
To:     <jic23@kernel.org>
CC:     <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <mcoquelin.stm32@gmail.com>,
        <alexandre.torgue@st.com>, <fabrice.gasnier@st.com>,
        <olivier.moysan@st.com>, <linux-iio@vger.kernel.org>,
        <lars@metafoo.de>, <knaack.h@gmx.de>, <pmeerw@pmeerw.net>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <etienne.carriere@st.com>
Subject: [PATCH 2/2] iio: dac: stm32-dac: better handle reset controller failures
Date:   Mon, 13 Jan 2020 14:14:26 +0100
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From: Etienne Carriere <etienne.carriere@st.com>

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>
---
 drivers/iio/dac/stm32-dac-core.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/dac/stm32-dac-core.c b/drivers/iio/dac/stm32-dac-core.c
index 4d93446..7e5809b 100644
--- 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);
-- 
2.7.4