[PATCH 0/2] iio: stm32-dfsdm-adc: fix filter & rate setting

[PATCH 0/2] iio: stm32-dfsdm-adc: fix filter & rate setting

[Fabrice Gasnier]

This series brings fixes to STM32 DFSDM ADC driver.

Fabrice Gasnier (2):
  iio: adc: stm32-dfsdm: fix successive oversampling settings
  iio: adc: stm32-dfsdm: fix sample rate for div2 spi clock

 drivers/iio/adc/stm32-dfsdm-adc.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

-- 
1.9.1

[PATCH 1/2] iio: adc: stm32-dfsdm: fix successive oversampling settings

[Fabrice Gasnier]

When doing successive oversampling settings, it may fail to update filter
parameters silently:
- First time oversampling is being set, it will be successful, as fl->res
is 0 initially.
- Next attempts with various oversamp value may return 0 (success), but
keep previous filter parameters, due to 'res' never reaches above or
equal current 'fl->res'.

This is particularly true when setting sampling frequency (that relies on
oversamp). Typical failure without error:
- run 1st test @16kHz samp freq will succeed
- run new test @8kHz will succeed as well
- run new test @16kHz (again): sample rate will remain 8kHz without error

Fixes: e2e6771c6462 ("IIO: ADC: add STM32 DFSDM sigma delta ADC support")

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
 drivers/iio/adc/stm32-dfsdm-adc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c
index 01422d1..dc911b6 100644
--- a/drivers/iio/adc/stm32-dfsdm-adc.c
+++ b/drivers/iio/adc/stm32-dfsdm-adc.c
@@ -144,6 +144,7 @@ static int stm32_dfsdm_set_osrs(struct stm32_dfsdm_filter *fl,
 	 * Leave as soon as if exact resolution if reached.
 	 * Otherwise the higher resolution below 32 bits is kept.
 	 */
+	fl->res = 0;
 	for (fosr = 1; fosr <= DFSDM_MAX_FL_OVERSAMPLING; fosr++) {
 		for (iosr = 1; iosr <= DFSDM_MAX_INT_OVERSAMPLING; iosr++) {
 			if (fast)
@@ -193,7 +194,7 @@ static int stm32_dfsdm_set_osrs(struct stm32_dfsdm_filter *fl,
 		}
 	}
 
-	if (!fl->fosr)
+	if (!fl->res)
 		return -EINVAL;
 
 	return 0;
-- 
1.9.1

[PATCH 2/2] iio: adc: stm32-dfsdm: fix sample rate for div2 spi clock

[Fabrice Gasnier]

When channel clk source is set to "CLKOUT_F" or "CLKOUT_R" (e.g. div2),
sample rate is currently set to half the requested value.

Fixes: eca949800d2d ("IIO: ADC: add stm32 DFSDM support for PDM
microphone")

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
 drivers/iio/adc/stm32-dfsdm-adc.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c
index dc911b6..b28a716 100644
--- a/drivers/iio/adc/stm32-dfsdm-adc.c
+++ b/drivers/iio/adc/stm32-dfsdm-adc.c
@@ -771,7 +771,7 @@ static int stm32_dfsdm_write_raw(struct iio_dev *indio_dev,
 	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
 	struct stm32_dfsdm_filter *fl = &adc->dfsdm->fl_list[adc->fl_id];
 	struct stm32_dfsdm_channel *ch = &adc->dfsdm->ch_list[chan->channel];
-	unsigned int spi_freq = adc->spi_freq;
+	unsigned int spi_freq;
 	int ret = -EINVAL;
 
 	switch (mask) {
@@ -785,8 +785,18 @@ static int stm32_dfsdm_write_raw(struct iio_dev *indio_dev,
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		if (!val)
 			return -EINVAL;
-		if (ch->src != DFSDM_CHANNEL_SPI_CLOCK_EXTERNAL)
+
+		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;
+		}
 
 		if (spi_freq % val)
 			dev_warn(&indio_dev->dev,
-- 
1.9.1

[PATCH 0/2] iio: stm32-dfsdm-adc: fix filter & rate setting

[Arnaud Pouliquen]

Hello,

For the series:
Acked-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>

Thanks,
Arnaud

On 03/13/2018 03:23 PM, Fabrice Gasnier wrote:
> This series brings fixes to STM32 DFSDM ADC driver.
> 
> Fabrice Gasnier (2):
>   iio: adc: stm32-dfsdm: fix successive oversampling settings
>   iio: adc: stm32-dfsdm: fix sample rate for div2 spi clock
> 
>  drivers/iio/adc/stm32-dfsdm-adc.c | 17 ++++++++++++++---
>  1 file changed, 14 insertions(+), 3 deletions(-)
> 

[PATCH 0/2] iio: stm32-dfsdm-adc: fix filter & rate setting

[Jonathan Cameron]

On Fri, 16 Mar 2018 10:10:09 +0100
Arnaud Pouliquen <arnaud.pouliquen@st.com> wrote:

> Hello,
> 
> For the series:
> Acked-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Both applied and marked for stable (as I'm not sure exactly when this will hit
mainline and it may be after the next merge window)

Thanks,

Jonathan

> 
> Thanks,
> Arnaud
> 
> On 03/13/2018 03:23 PM, Fabrice Gasnier wrote:
> > This series brings fixes to STM32 DFSDM ADC driver.
> > 
> > Fabrice Gasnier (2):
> >   iio: adc: stm32-dfsdm: fix successive oversampling settings
> >   iio: adc: stm32-dfsdm: fix sample rate for div2 spi clock
> > 
> >  drivers/iio/adc/stm32-dfsdm-adc.c | 17 ++++++++++++++---
> >  1 file changed, 14 insertions(+), 3 deletions(-)
> >