[PATCH 3/3] iio: adc: ti-ads8344: optimize consumption

[Alexandre Belloni]

Set the clock mode only once, at probe time and then keep the ADC powered
down between conversions.

Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
---
 drivers/iio/adc/ti-ads8344.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/ti-ads8344.c b/drivers/iio/adc/ti-ads8344.c
index 9b2d3a8ea6bd..0804650d8d8a 100644
--- a/drivers/iio/adc/ti-ads8344.c
+++ b/drivers/iio/adc/ti-ads8344.c
@@ -65,7 +65,7 @@ static const struct iio_chan_spec ads8344_channels[] = {
 };
 
 static int ads8344_adc_conversion(struct ads8344 *adc, int channel,
-				  bool differential)
+				  bool differential, u8 clock)
 {
 	struct spi_device *spi = adc->spi;
 	int ret;
@@ -75,7 +75,7 @@ static int ads8344_adc_conversion(struct ads8344 *adc, int channel,
 	if (!differential)
 		buf[0] |= ADS8344_SINGLE_END;
 	buf[0] |= ADS8344_CHANNEL(channel);
-	buf[0] |= ADS8344_CLOCK_INTERNAL;
+	buf[0] |= clock;
 
 	ret = spi_write(spi, buf, 1);
 	if (ret)
@@ -100,7 +100,7 @@ static int ads8344_read_raw(struct iio_dev *iio,
 	case IIO_CHAN_INFO_RAW:
 		mutex_lock(&adc->lock);
 		*value = ads8344_adc_conversion(adc, channel->scan_index,
-						channel->differential);
+						channel->differential, 0);
 		mutex_unlock(&adc->lock);
 		if (*value < 0)
 			return *value;
@@ -155,6 +155,11 @@ static int ads8344_probe(struct spi_device *spi)
 	if (ret)
 		return ret;
 
+	/* Do a dummy read and set external clock mode */
+	ret = ads8344_adc_conversion(adc, 0, 0, ADS8344_CLOCK_INTERNAL);
+	if (ret < 0)
+		return ret;
+
 	spi_set_drvdata(spi, indio_dev);
 
 	ret = iio_device_register(indio_dev);
-- 
2.25.2