Re: [PATCH v8 08/11] iio: adc: ad7768-1: add support for Synchronization over SPI

[Andy Shevchenko <andy@kernel.org>]

On Thu, May 15, 2025 at 06:13:56PM -0300, Jonathan Santos wrote:
> The synchronization method using GPIO requires the generated pulse to be
> truly synchronous with the base MCLK signal. When it is not possible to
> do that in hardware, the datasheet recommends using synchronization over
> SPI, where the generated pulse is already synchronous with MCLK. This
> requires the SYNC_OUT pin to be connected to the SYNC_IN pin.
> 
> Use trigger-sources property to enable device synchronization over SPI
> and multi-device synchronization while replacing sync-in-gpios property.

...

> +static int ad7768_trigger_sources_get_sync(struct device *dev,
> +					   struct ad7768_state *st)
> +{
> +	struct fwnode_reference_args args;
> +	struct fwnode_handle *fwnode = dev_fwnode(dev);
> +	int ret;
> +
> +	/*
> +	 * The AD7768-1 allows two primary methods for driving the SYNC_IN pin
> +	 * to synchronize one or more devices:
> +	 * 1. Using an external GPIO.
> +	 * 2. Using a SPI command, where the SYNC_OUT pin generates a
> +	 *    synchronization pulse that drives the SYNC_IN pin.
> +	 */
> +	if (!fwnode_property_present(fwnode, "trigger-sources")) {

I'm wondering if you can split the below to a separate function and do something like

	if (fwnode_property_present(...))
		return setup_trigger_source(...);

	...
	en_spi_sync = true;
	return 0;

> +		/*
> +		 * In the absence of trigger-sources property, enable self
> +		 * synchronization over SPI (SYNC_OUT).
> +		 */
> +		st->en_spi_sync = true;
> +		return 0;
> +	}
> +
> +	ret = fwnode_property_get_reference_args(fwnode,
> +						 "trigger-sources",
> +						 "#trigger-source-cells",
> +						 0,
> +						 AD7768_TRIGGER_SOURCE_SYNC_IDX,
> +						 &args);


__free(fwnode_handle) ?

> +	if (ret)
> +		return ret;
> +
> +	fwnode = args.fwnode;
> +	/* First, try getting the GPIO trigger source */
> +	if (fwnode_device_is_compatible(fwnode, "gpio-trigger")) {
> +		st->gpio_sync_in = devm_fwnode_gpiod_get_index(dev, fwnode,
> +							       NULL,
> +							       0,
> +							       GPIOD_OUT_LOW,
> +							       "sync-in");
> +		ret = PTR_ERR_OR_ZERO(st->gpio_sync_in);
> +		goto out_put_node;
> +	}
> +
> +	/*
> +	 * TODO: Support the other cases when we have a trigger subsystem to
> +	 * reliably handle other types of devices as trigger sources.
> +	 *
> +	 * For now, return an error message. For self triggering, omit the
> +	 * trigger-sources property.
> +	 */
> +	ret = dev_err_probe(dev, -EOPNOTSUPP, "Invalid synchronization trigger source\n");
> +
> +out_put_node:

The above will allow to get rid of this label.

> +	fwnode_handle_put(args.fwnode);
> +	return ret;
> +}

-- 
With Best Regards,
Andy Shevchenko