linux-kernel - [INTERNAL][PATCH] iio: adc: stm32-dfsdm: adapt sampling rate to oversampling ratio

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Message-ID: <20191127100712.24558-1-olivier.moysan@st.com>
Date:   Wed, 27 Nov 2019 11:07:12 +0100
From:   Olivier Moysan <olivier.moysan@...com>
To:     <jic23@...nel.org>, <knaack.h@....de>, <lars@...afoo.de>,
        <pmeerw@...erw.net>, <mcoquelin.stm32@...il.com>,
        <alexandre.torgue@...com>, <fabrice.gasnier@...com>,
        <linux-iio@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <benjamin.gaignard@...com>,
        <olivier.moysan@...com>
Subject: [INTERNAL][PATCH] iio: adc: stm32-dfsdm: adapt sampling rate to oversampling ratio

Update sampling rate when oversampling ratio is changed
through the IIO ABI.

Signed-off-by: Olivier Moysan <olivier.moysan@...com>
---
 drivers/iio/adc/stm32-dfsdm-adc.c | 32 ++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c
index 0339ecdd06bd..87a842507509 100644
--- a/drivers/iio/adc/stm32-dfsdm-adc.c
+++ b/drivers/iio/adc/stm32-dfsdm-adc.c
@@ -1221,14 +1221,32 @@ static int stm32_dfsdm_write_raw(struct iio_dev *indio_dev,
 	unsigned int spi_freq;
 	int ret = -EINVAL;
 
+	switch (ch->src) {
+	case DFSDM_CHANNEL_SPI_CLOCK_INTERNAL:
+		spi_freq = adc->dfsdm->spi_master_freq;
+		break;
+	case DFSDM_CHANNEL_SPI_CLOCK_INTERNAL_DIV2_FALLING:
+	case DFSDM_CHANNEL_SPI_CLOCK_INTERNAL_DIV2_RISING:
+		spi_freq = adc->dfsdm->spi_master_freq / 2;
+		break;
+	default:
+		spi_freq = adc->spi_freq;
+	}
+
 	switch (mask) {
 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
 		ret = iio_device_claim_direct_mode(indio_dev);
 		if (ret)
 			return ret;
+
 		ret = stm32_dfsdm_compute_all_osrs(indio_dev, val);
-		if (!ret)
+		if (!ret) {
+			dev_dbg(&indio_dev->dev,
+				"Sampling rate changed from (%u) to (%u)\n",
+				adc->sample_freq, spi_freq / val);
 			adc->oversamp = val;
+			adc->sample_freq = spi_freq / val;
+		}
 		iio_device_release_direct_mode(indio_dev);
 		return ret;
 
@@ -1240,18 +1258,6 @@ static int stm32_dfsdm_write_raw(struct iio_dev *indio_dev,
 		if (ret)
 			return ret;
 
-		switch (ch->src) {
-		case DFSDM_CHANNEL_SPI_CLOCK_INTERNAL:
-			spi_freq = adc->dfsdm->spi_master_freq;
-			break;
-		case DFSDM_CHANNEL_SPI_CLOCK_INTERNAL_DIV2_FALLING:
-		case DFSDM_CHANNEL_SPI_CLOCK_INTERNAL_DIV2_RISING:
-			spi_freq = adc->dfsdm->spi_master_freq / 2;
-			break;
-		default:
-			spi_freq = adc->spi_freq;
-		}
-
 		ret = dfsdm_adc_set_samp_freq(indio_dev, val, spi_freq);
 		iio_device_release_direct_mode(indio_dev);
 		return ret;
-- 
2.17.1