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

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Message-ID: <c2c2a902-c16b-e85e-7fa7-a86d88f7a159@st.com>
Date:   Wed, 27 Nov 2019 17:13:28 +0100
From:   Fabrice Gasnier <fabrice.gasnier@...com>
To:     Olivier Moysan <olivier.moysan@...com>, <jic23@...nel.org>,
        <knaack.h@....de>, <lars@...afoo.de>, <pmeerw@...erw.net>,
        <mcoquelin.stm32@...il.com>, <alexandre.torgue@...com>,
        <linux-iio@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <benjamin.gaignard@...com>
Subject: Re: [PATCH v2] iio: adc: stm32-dfsdm: adapt sampling rate to
 oversampling ratio

On 11/27/19 2:10 PM, Olivier Moysan wrote:
> Update sampling rate when oversampling ratio is changed
> through the IIO ABI.
> 
> Signed-off-by: Olivier Moysan <olivier.moysan@...com>

Hi Olivier,

Acked-by: Fabrice Gasnier <fabrice.gasnier@...com>

Thanks,
Fabrice
> ---
> 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;
>