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SubjectRe: [PATCH 3/5] iio: adc: stm32-dfsdm: manage data resolution in trigger mode
On Wed, 19 Jun 2019 15:03:49 +0200
Olivier Moysan <olivier.moysan@st.com> wrote:

> Add output sample resolution management in scan mode.
> Add stm32_dfsdm_process_data() function to share sample
> processing between continuous and trigger modes.
>
> Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Makes sense, though I would have preferred a little bit more info
on what the user visible effects fo this change are in
the patch description. I think I know from reading the code,
but not every one will do that ;)

Applied to the togreg branch of iio.git and pushed out as
testing for the autobuilders to play with it.

Thanks,

Jonathan

> ---
> drivers/iio/adc/stm32-dfsdm-adc.c | 41 ++++++++++++++++++++++++++-------------
> 1 file changed, 28 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c
> index 6b90a40882f2..5b19a88412a6 100644
> --- a/drivers/iio/adc/stm32-dfsdm-adc.c
> +++ b/drivers/iio/adc/stm32-dfsdm-adc.c
> @@ -779,6 +779,30 @@ static unsigned int stm32_dfsdm_adc_dma_residue(struct stm32_dfsdm_adc *adc)
> return 0;
> }
>
> +static inline void stm32_dfsdm_process_data(struct stm32_dfsdm_adc *adc,
> + s32 *buffer)
> +{
> + struct stm32_dfsdm_filter *fl = &adc->dfsdm->fl_list[adc->fl_id];
> + struct stm32_dfsdm_filter_osr *flo = &fl->flo;
> + unsigned int i = adc->nconv;
> + s32 *ptr = buffer;
> +
> + while (i--) {
> + /* Mask 8 LSB that contains the channel ID */
> + *ptr &= 0xFFFFFF00;
> + /* Convert 2^(n-1) sample to 2^(n-1)-1 to avoid wrap-around */
> + if (*ptr > flo->max)
> + *ptr -= 1;
> + /*
> + * Samples from filter are retrieved with 23 bits resolution
> + * or less. Shift left to align MSB on 24 bits.
> + */
> + *ptr <<= flo->lshift;
> +
> + ptr++;
> + }
> +}
> +
> static irqreturn_t stm32_dfsdm_adc_trigger_handler(int irq, void *p)
> {
> struct iio_poll_func *pf = p;
> @@ -787,7 +811,9 @@ static irqreturn_t stm32_dfsdm_adc_trigger_handler(int irq, void *p)
> int available = stm32_dfsdm_adc_dma_residue(adc);
>
> while (available >= indio_dev->scan_bytes) {
> - u32 *buffer = (u32 *)&adc->rx_buf[adc->bufi];
> + s32 *buffer = (s32 *)&adc->rx_buf[adc->bufi];
> +
> + stm32_dfsdm_process_data(adc, buffer);
>
> iio_push_to_buffers_with_timestamp(indio_dev, buffer,
> pf->timestamp);
> @@ -806,8 +832,6 @@ static void stm32_dfsdm_dma_buffer_done(void *data)
> {
> struct iio_dev *indio_dev = data;
> struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> - struct stm32_dfsdm_filter *fl = &adc->dfsdm->fl_list[adc->fl_id];
> - struct stm32_dfsdm_filter_osr *flo = &fl->flo;
> int available = stm32_dfsdm_adc_dma_residue(adc);
> size_t old_pos;
>
> @@ -832,16 +856,7 @@ static void stm32_dfsdm_dma_buffer_done(void *data)
> while (available >= indio_dev->scan_bytes) {
> s32 *buffer = (s32 *)&adc->rx_buf[adc->bufi];
>
> - /* Mask 8 LSB that contains the channel ID */
> - *buffer &= 0xFFFFFF00;
> - /* Convert 2^(n-1) sample to 2^(n-1)-1 to avoid wrap-around */
> - if (*buffer > flo->max)
> - *buffer -= 1;
> - /*
> - * Samples from filter are retrieved with 23 bits resolution
> - * or less. Shift left to align MSB on 24 bits.
> - */
> - *buffer <<= flo->lshift;
> + stm32_dfsdm_process_data(adc, buffer);
>
> available -= indio_dev->scan_bytes;
> adc->bufi += indio_dev->scan_bytes;

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