[PATCH v2] iio: adc: stm32-dfsdm: adapt sampling rate to oversampling ratio

Olivier Moysan
2019-11-27T13:10:44Z

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

Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
---
changes in version 2:
- correct title
---
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