Re: [PATCH 3/3] iio: adc: ti-ads1298: Don't enable internal test signal during init

[mike.looijmans]

On 5/6/26 20:15, Md Shofiqul Islam wrote:
> The driver was enabling the internal test signal (INT_TEST), double
> amplitude (TEST_AMP), and fast frequency (TEST_FREQ_FAST) bits in
> CONFIG2 during initialization. These bits activate an internal square
> wave generator intended for device testing and calibration, not normal
> ECG operation.
>
> While the test signal does not affect channel measurements unless the
> channel MUX is explicitly set to route it (MUX = 101), enabling the
> test signal generator unnecessarily increases power consumption and is
> inappropriate for a medical ADC driver in normal operation.
>
> Keep only the RESERVED bit which the datasheet requires to always be
> written as 1.

This boils down to just leaving the register at its default value. In that 
case, I'd suggest removing this completely.

> Signed-off-by: Md Shofiqul Islam <shofiqtest@xxxxxxxxx>
> ---
>   drivers/iio/adc/ti-ads1298.c | 7 ++-----
>   1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/iio/adc/ti-ads1298.c b/drivers/iio/adc/ti-ads1298.c
> index 186bda3087..360dfd2fc8 100644
> --- a/drivers/iio/adc/ti-ads1298.c
> +++ b/drivers/iio/adc/ti-ads1298.c
> @@ -615,12 +615,9 @@ static int ads1298_init(struct iio_dev *indio_dev)
>   	if (!indio_dev->name)
>   		return -ENOMEM;
>   
> -	/* Enable internal test signal, double amplitude, double frequency */
> +	/* CONFIG2: reserved bit must always be written as 1 per datasheet */
>   	ret = regmap_write(priv->regmap, ADS1298_REG_CONFIG2,
> -			   ADS1298_MASK_CONFIG2_RESERVED |
> -			   ADS1298_MASK_CONFIG2_INT_TEST |
> -			   ADS1298_MASK_CONFIG2_TEST_AMP |
> -			   ADS1298_MASK_CONFIG2_TEST_FREQ_FAST);
> +			   ADS1298_MASK_CONFIG2_RESERVED);
>   	if (ret)
>   		return ret;
>   


--
Mike Looijmans
System Expert

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