linux-kernel - [PATCH] iio: adc: stm32: fix vrefint wrong calibration value handling

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Date:   Thu, 9 Jun 2022 11:58:56 +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] iio: adc: stm32: fix vrefint wrong calibration value handling

If the vrefint calibration is zero, the vrefint channel output value
cannot be computed. Currently, in such case, the raw conversion value
is returned, which is not relevant.
Do not expose the vrefint channel when the output value cannot be
computed, instead.

Fixes: 0e346b2cfa85 ("iio: adc: stm32-adc: add vrefint calibration support")

Signed-off-by: Olivier Moysan <olivier.moysan@...s.st.com>
---
 drivers/iio/adc/stm32-adc.c | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index a68ecbda6480..f13c112f540f 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -1365,7 +1365,7 @@ static int stm32_adc_read_raw(struct iio_dev *indio_dev,
 		else
 			ret = -EINVAL;
 
-		if (mask == IIO_CHAN_INFO_PROCESSED && adc->vrefint.vrefint_cal)
+		if (mask == IIO_CHAN_INFO_PROCESSED)
 			*val = STM32_ADC_VREFINT_VOLTAGE * adc->vrefint.vrefint_cal / *val;
 
 		iio_device_release_direct_mode(indio_dev);
@@ -1979,10 +1979,10 @@ static int stm32_adc_populate_int_ch(struct iio_dev *indio_dev, const char *ch_n
 
 	for (i = 0; i < STM32_ADC_INT_CH_NB; i++) {
 		if (!strncmp(stm32_adc_ic[i].name, ch_name, STM32_ADC_CH_SZ)) {
-			adc->int_ch[i] = chan;
-
-			if (stm32_adc_ic[i].idx != STM32_ADC_INT_CH_VREFINT)
-				continue;
+			if (stm32_adc_ic[i].idx != STM32_ADC_INT_CH_VREFINT) {
+				adc->int_ch[i] = chan;
+				break;
+			}
 
 			/* Get calibration data for vrefint channel */
 			ret = nvmem_cell_read_u16(&indio_dev->dev, "vrefint", &vrefint);
@@ -1990,10 +1990,15 @@ static int stm32_adc_populate_int_ch(struct iio_dev *indio_dev, const char *ch_n
 				return dev_err_probe(indio_dev->dev.parent, ret,
 						     "nvmem access error\n");
 			}
-			if (ret == -ENOENT)
-				dev_dbg(&indio_dev->dev, "vrefint calibration not found\n");
-			else
-				adc->vrefint.vrefint_cal = vrefint;
+			if (ret == -ENOENT) {
+				dev_dbg(&indio_dev->dev, "vrefint calibration not found. Skip vrefint channel\n");
+				return ret;
+			} else if (!vrefint) {
+				dev_dbg(&indio_dev->dev, "Null vrefint calibration value. Skip vrefint channel\n");
+				return -ENOENT;
+			}
+			adc->int_ch[i] = chan;
+			adc->vrefint.vrefint_cal = vrefint;
 		}
 	}
 
@@ -2030,7 +2035,9 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
 			}
 			strncpy(adc->chan_name[val], name, STM32_ADC_CH_SZ);
 			ret = stm32_adc_populate_int_ch(indio_dev, name, val);
-			if (ret)
+			if (ret == -ENOENT)
+				continue;
+			else if (ret)
 				goto err;
 		} else if (ret != -EINVAL) {
 			dev_err(&indio_dev->dev, "Invalid label %d\n", ret);
-- 
2.25.1