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| author | Olivier Moysan <olivier.moysan@st.com> | 2019-06-19 15:03:51 +0200 |
|---|---|---|
| committer | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2019-06-22 10:32:43 +0100 |
| commit | 18eaffab90eb3c2280986bb546e571adc85756d5 (patch) | |
| tree | c1d73fae875273cecadc67e250516a6edb39f2c9 | |
| parent | d716204fd5472631970aa927c773c3302ac70fbe (diff) | |
| download | linux-18eaffab90eb3c2280986bb546e571adc85756d5.tar.bz2 | |
iio: adc: stm32-dfsdm: add comment for 16 bits record
Add a comment on DMA configuration for 16 bits record.
Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Acked-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
| -rw-r--r-- | drivers/iio/adc/stm32-dfsdm-adc.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c index d855a605eab6..ee1e0569d0e1 100644 --- a/drivers/iio/adc/stm32-dfsdm-adc.c +++ b/drivers/iio/adc/stm32-dfsdm-adc.c @@ -918,6 +918,11 @@ static void stm32_dfsdm_dma_buffer_done(void *data) static int stm32_dfsdm_adc_dma_start(struct iio_dev *indio_dev) { struct stm32_dfsdm_adc *adc = iio_priv(indio_dev); + /* + * The DFSDM supports half-word transfers. However, for 16 bits record, + * 4 bytes buswidth is kept, to avoid losing samples LSBs when left + * shift is required. + */ struct dma_slave_config config = { .src_addr = (dma_addr_t)adc->dfsdm->phys_base, .src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES, |