Re: [PATCH v2 09/14] iio: accel: adxl345: extend sample frequency adjustments

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 10 Feb 2025 11:01:14 +0000
Lothar Rubusch <l.rubusch@gmail.com> wrote:

> Introduce enums and functions to work with the sample frequency
> adjustments. Let the sample frequency adjust via IIO and configure
> a reasonable default.
> 
> Replace the old static sample frequency handling. The patch is in
> preparation for activity/inactivity handling.
> 
> Signed-off-by: Lothar Rubusch <l.rubusch@gmail.com>

I noticed now that we don't actually have regmap caching enabled.
I think it will make things sufficiently simpler that it is worth
doing even though you have to specify which registers are volatile etc.


> +
> +static int adxl345_set_odr(struct adxl345_state *st, enum adxl345_odr odr)
> +{
> +	int ret;
> +
> +	ret = regmap_update_bits(st->regmap, ADXL345_REG_BW_RATE,
> +				 ADXL345_BW_RATE_MSK,
> +				 FIELD_PREP(ADXL345_BW_RATE_MSK, odr));
> +	if (ret)
> +		return ret;
> +
> +	st->odr = odr;
Why do we need to keep a copy cached? Seems like we can get it from
regmap cache easily enough?

> +
> +	return 0;
> +}

> @@ -488,7 +572,12 @@ static int adxl345_write_raw(struct iio_dev *indio_dev,
>  			     int val, int val2, long mask)
>  {
>  	struct adxl345_state *st = iio_priv(indio_dev);
> -	s64 n;
> +	enum adxl345_odr odr;
> +	int ret;
> +
> +	ret = adxl345_set_measure_en(st, false);

Please add some more on why this is now necessary to the patch description.

> +	if (ret)
> +		return ret;
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_CALIBBIAS:
> @@ -496,20 +585,24 @@ static int adxl345_write_raw(struct iio_dev *indio_dev,
>  		 * 8-bit resolution at +/- 2g, that is 4x accel data scale
>  		 * factor
>  		 */
> -		return regmap_write(st->regmap,
> -				    ADXL345_REG_OFS_AXIS(chan->address),
> -				    val / 4);
> +		ret = regmap_write(st->regmap,
> +				   ADXL345_REG_OFS_AXIS(chan->address),
> +				   val / 4);
> +		break;
>  	case IIO_CHAN_INFO_SAMP_FREQ:
> -		n = div_s64(val * NANOHZ_PER_HZ + val2,
> -			    ADXL345_BASE_RATE_NANO_HZ);
> -
> -		return regmap_update_bits(st->regmap, ADXL345_REG_BW_RATE,
> -					  ADXL345_BW_RATE,
> -					  clamp_val(ilog2(n), 0,
> -						    ADXL345_BW_RATE));
> +		ret = adxl345_find_odr(st, val, val2, &odr);
> +		if (ret)
> +			return ret;
> +		ret = adxl345_set_odr(st, odr);
> +		break;
> +	default:
> +		return -EINVAL;
>  	}
>  
> -	return -EINVAL;
> +	if (ret)
> +		return ret;
> +
> +	return adxl345_set_measure_en(st, true);
>  }