linux-kernel - [PATCH 1/2] iio: adc: stm32-adc: make safe adc disable

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Date:   Mon, 20 Jun 2022 17:47:37 +0200
From:   Olivier Moysan <olivier.moysan@...s.st.com>
To:     Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Fabrice Gasnier <fabrice.gasnier@...s.st.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Olivier Moysan <olivier.moysan@...s.st.com>,
        Paul Cercueil <paul@...pouillou.net>,
        Wan Jiabing <wanjiabing@...o.com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>
Subject: [PATCH 1/2] iio: adc: stm32-adc: make safe adc disable

>From ADC reference manual the software is allowed to write the
control bit ADDIS of the ADC_CR register only if the ADC is enabled.
Return immediately from stm32h7_adc_disable() if ADC is already disabled.

Signed-off-by: Olivier Moysan <olivier.moysan@...s.st.com>
---
 drivers/iio/adc/stm32-adc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index a68ecbda6480..80e333f65ddd 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -876,6 +876,9 @@ static void stm32h7_adc_disable(struct iio_dev *indio_dev)
 	int ret;
 	u32 val;
 
+	if (!(stm32_adc_readl(adc, STM32H7_ADC_CR) & STM32H7_ADEN))
+		return;
+
 	/* Disable ADC and wait until it's effectively disabled */
 	stm32_adc_set_bits(adc, STM32H7_ADC_CR, STM32H7_ADDIS);
 	ret = stm32_adc_readl_poll_timeout(STM32H7_ADC_CR, val,
-- 
2.25.1