linux-kernel - [PATCH v3 05/19] iio: adc: at91-sama5d2_adc: exit from write

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Date:   Wed, 3 Aug 2022 13:28:41 +0300
From:   Claudiu Beznea <claudiu.beznea@...rochip.com>
To:     <eugen.hristev@...rochip.com>, <jic23@...nel.org>,
        <lars@...afoo.de>, <nicolas.ferre@...rochip.com>,
        <alexandre.belloni@...tlin.com>, <ludovic.desroches@...rochip.com>,
        <robh+dt@...nel.org>
CC:     <linux-iio@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>
Subject: [PATCH v3 05/19] iio: adc: at91-sama5d2_adc: exit from write_raw() when buffers are enabled

When buffers are enabled conversion may start asynchronously thus
allowing changes on actual hardware could lead to bad behavior. Thus
do not allow changing oversampling ratio and sample frequency when
if iio_device_claim_direct_mode() returns with error.

Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>
---
 drivers/iio/adc/at91-sama5d2_adc.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index e2c82c5a2fac..64943d8ea869 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -1641,6 +1641,7 @@ static int at91_adc_write_raw(struct iio_dev *indio_dev,
 			      int val, int val2, long mask)
 {
 	struct at91_adc_state *st = iio_priv(indio_dev);
+	int ret;
 
 	switch (mask) {
 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
@@ -1650,20 +1651,29 @@ static int at91_adc_write_raw(struct iio_dev *indio_dev,
 		/* if no change, optimize out */
 		if (val == st->oversampling_ratio)
 			return 0;
+
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
 		mutex_lock(&st->lock);
 		st->oversampling_ratio = val;
 		/* update ratio */
 		at91_adc_config_emr(st);
 		mutex_unlock(&st->lock);
+		iio_device_release_direct_mode(indio_dev);
 		return 0;
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		if (val < st->soc_info.min_sample_rate ||
 		    val > st->soc_info.max_sample_rate)
 			return -EINVAL;
 
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
 		mutex_lock(&st->lock);
 		at91_adc_setup_samp_freq(indio_dev, val);
 		mutex_unlock(&st->lock);
+		iio_device_release_direct_mode(indio_dev);
 		return 0;
 	default:
 		return -EINVAL;
-- 
2.34.1