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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Fabrice Gasnier <fabrice.gasnier@st.com>,
        Stable@vger.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>
Subject: [PATCH 4.14 21/54] iio: adc: stm32: fix stm32h7_adc_enable error handling
Date:   Mon, 26 Feb 2018 21:21:58 +0100
Message-Id: <20180226202145.463670002@linuxfoundation.org>
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4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Fabrice Gasnier <fabrice.gasnier@st.com>

commit a3b5655ebdb501a98a45c0d3265dca9f2fe0218a upstream.

Error handling in stm32h7_adc_enable routine doesn't unwind enable
sequence correctly. ADEN can only be cleared by hardware (e.g. by
writing one to ADDIS).
It's also better to clear ADRDY just after it's been set by hardware.

Fixes: 95e339b6e85d ("iio: adc: stm32: add support for STM32H7")

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/iio/adc/stm32-adc.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -764,8 +764,6 @@ static int stm32h7_adc_enable(struct stm
 	int ret;
 	u32 val;
 
-	/* Clear ADRDY by writing one, then enable ADC */
-	stm32_adc_set_bits(adc, STM32H7_ADC_ISR, STM32H7_ADRDY);
 	stm32_adc_set_bits(adc, STM32H7_ADC_CR, STM32H7_ADEN);
 
 	/* Poll for ADRDY to be set (after adc startup time) */
@@ -773,8 +771,11 @@ static int stm32h7_adc_enable(struct stm
 					   val & STM32H7_ADRDY,
 					   100, STM32_ADC_TIMEOUT_US);
 	if (ret) {
-		stm32_adc_clr_bits(adc, STM32H7_ADC_CR, STM32H7_ADEN);
+		stm32_adc_set_bits(adc, STM32H7_ADC_CR, STM32H7_ADDIS);
 		dev_err(&indio_dev->dev, "Failed to enable ADC\n");
+	} else {
+		/* Clear ADRDY by writing one */
+		stm32_adc_set_bits(adc, STM32H7_ADC_ISR, STM32H7_ADRDY);
 	}
 
 	return ret;