Re: [PATCH v5 09/20] iio: adc: ad7768: Configure channel sampling profiles

[Andy Shevchenko]

On Fri, Aug 28, 2026 at 05:30:32PM +0200, Janani Sunil wrote:
> At buffered capture setup, select the fastest compatible power mode for
> the enabled channel rates. Group channels into the two hardware mode
> profiles and program their decimation, mode selection, and data clock.

...

> +static int ad7768_set_lowest_noise_mode(struct ad7768_state *st,
> +					const unsigned long *scan_mask)
> +{
> +	/*
> +	 * The output data rate ranges overlap between the power modes. At a
> +	 * common ODR, the faster mode has lower noise, so prefer the fastest
> +	 * mode that supports every enabled channel.
> +	 */
> +	for (unsigned int mode_idx = ARRAY_SIZE(ad7768_power_modes);
> +	     mode_idx-- > 0;) {

This is rather unusual pattern, better to have this as simple as

	unsigned int mode_idx = ARRAY_SIZE(ad7768_power_modes);

	while (mode_idx --) {

> +		bool supported = true;
> +		unsigned int channel;
> +
> +		for_each_set_bit(channel, scan_mask,
> +				 st->chip_info->num_channels) {
> +			if (!ad7768_find_freq_config(st, mode_idx,
> +						     st->ch_freq[channel])) {
> +				supported = false;
> +				break;
> +			}
> +		}
> +
> +		if (supported)
> +			return ad7768_set_power_mode(st, mode_idx);
> +	}
> +
> +	return -EINVAL;
> +}

...

> +static int ad7768_apply_channel_modes(struct iio_dev *indio_dev,
> +				      const unsigned long *scan_mask)
>  {
> +	unsigned int mode_freq[AD7768_NUM_CHANNEL_MODES] = { };
> +	bool mode_used[AD7768_NUM_CHANNEL_MODES] = { };
>  	struct ad7768_state *st = iio_priv(indio_dev);
> +	struct device *dev = indio_dev->dev.parent;
>  	unsigned long channel_mask;
>  	unsigned long standby_mask;
> +	unsigned int max_freq = 0;

Split assignment, also see below.

> +	unsigned int c;
>  	int ret;

...

	max_freq = 0;

> +	for (unsigned int mode = 0; mode < AD7768_NUM_CHANNEL_MODES; mode++) {
> +		if (!mode_used[mode])
> +			continue;
> +
> +		ret = ad7768_set_mode_decimation(st, mode_freq[mode], mode);
> +		if (ret)
> +			return ret;
> +
> +		ret = regmap_clear_bits(st->regmap, AD7768_REG_CH_MODE(mode),
> +					AD7768_CH_MODE_FILTER_TYPE_MSK);
> +		if (ret)
> +			return ret;
> +
> +		max_freq = max(max_freq, mode_freq[mode]);
> +	}
> +
> +	ret = ad7768_set_clk_divs(st, max_freq);
> +	if (ret)
> +		return ret;
> +
> +	return ad7768_sync(st);
> +}

-- 
With Best Regards,
Andy Shevchenko