Re: [PATCH v4 3/3] iio: adc: ti-ads1298: Remove unnecessary CONFIG2 write during init

[David Lechner]

On 5/9/26 10:19 AM, 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.
> 
> CONFIG2 defaults to having only the RESERVED bit set after reset, which
> is the correct value for normal operation. Remove the write entirely
> since it would just be writing the reset default value.
> 
> Suggested-by: Mike Looijmans <mike.looijmans@xxxxxxxx>
> Signed-off-by: Md Shofiqul Islam <shofiqtest@xxxxxxxxx>
> ---
>  drivers/iio/adc/ti-ads1298.c | 9 ---------
>  1 file changed, 9 deletions(-)
> 
> diff --git a/drivers/iio/adc/ti-ads1298.c b/drivers/iio/adc/ti-ads1298.c
> index 186bda3087..8957e873e1 100644
> --- a/drivers/iio/adc/ti-ads1298.c
> +++ b/drivers/iio/adc/ti-ads1298.c
> @@ -615,15 +615,6 @@ static int ads1298_init(struct iio_dev *indio_dev)
>  	if (!indio_dev->name)
>  		return -ENOMEM;
>  
> -	/* Enable internal test signal, double amplitude, double frequency */

This is why comments should say why and not what. If the original author
had a plan for this, we don't know what it was.

I look at the datasheet and the driver. Seems OK since the test signals
aren't used anywhere in the driver right now. 

> -	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);
> -	if (ret)
> -		return ret;
> -
>  	val = ADS1298_MASK_CONFIG3_RESERVED; /* Must write 1 always */
>  	if (!priv->reg_vref) {
>  		/* Enable internal reference */