Re: [PATCH 10/12] iio: dac: ad5686: add triggered buffer support

[Andy Shevchenko <andriy.shevchenko@intel.com>]

On Tue, Jun 02, 2026 at 05:33:57PM +0100, Rodrigo Alencar via B4 Relay wrote:

> Implement trigger handler by leveraging the LDAC gpio to update all DAC
> channels at once when it is available. Also, the multiple channel writes
> can be flushed at once with the sync() operation.

...

> +static irqreturn_t ad5686_trigger_handler(int irq, void *p)
> +{
> +	struct iio_poll_func *pf = p;
> +	struct iio_dev *indio_dev = pf->indio_dev;
> +	struct iio_buffer *buffer = indio_dev->buffer;
> +	struct ad5686_state *st = iio_priv(indio_dev);
> +	u16 val[AD5686_MAX_CHANNELS] = { };
> +	int ret, ch, i = 0;
> +	bool async_update;
> +	u8 cmd;
> +
> +	ret = iio_pop_from_buffer(buffer, val);
> +	if (ret)
> +		goto out;
> +
> +	mutex_lock(&st->lock);
> +
> +	async_update = st->ldac_gpio && bitmap_weight(indio_dev->active_scan_mask,
> +						      iio_get_masklength(indio_dev)) > 1;

Easier to read on a logical split

	async_update = st->ldac_gpio &&
		       bitmap_weight(indio_dev->active_scan_mask, iio_get_masklength(indio_dev)) > 1;

Or with a temporary variable where you keep the weight of the bitmap.

> +	if (async_update) {
> +		/* use ldac to update all channels simultaneously */
> +		cmd = AD5686_CMD_WRITE_INPUT_N;
> +		gpiod_set_value_cansleep(st->ldac_gpio, 0);
> +	} else {
> +		cmd = AD5686_CMD_WRITE_INPUT_N_UPDATE_N;
> +	}
> +
> +	iio_for_each_active_channel(indio_dev, ch) {
> +		ret = st->ops->write(st, cmd, indio_dev->channels[ch].address, val[i++]);
> +		if (ret)
> +			goto cleanup;
> +	}
> +
> +	if (st->ops->sync)
> +		ret = st->ops->sync(st); /* flush all pending transfers */

> +cleanup:

Bad label naming. Also may clash in the future with some overflow or wrap traps
(you can find interesting discussion with Linus on the implementation of that
 with Kees).

> +	if (async_update)
> +		gpiod_set_value_cansleep(st->ldac_gpio, 1);
> +
> +	mutex_unlock(&st->lock);
> +out:

out_notify_done:

> +	iio_trigger_notify_done(indio_dev->trig);
> +
> +	return IRQ_HANDLED;
> +}

-- 
With Best Regards,
Andy Shevchenko