On Fri, Nov 26, 2021 at 10:01:07AM +0100, Martin Kepplinger wrote:

> +	dw9714_dev->vcc = devm_regulator_get_optional(&client->dev, "vcc");
> +	if (IS_ERR(dw9714_dev->vcc)) {
> +		dev_dbg(&client->dev, "No vcc regulator found: %ld\n",
> +			PTR_ERR(dw9714_dev->vcc));
> +		dw9714_dev->vcc = NULL;
> +	}

To repeat my original feedback: unless the supply can be physically
absent you should use regulator_get().   The _optional variants are only
for cases where the supply might be physically absent.