Re: [PATCH v3 3/3] iio: light: isl29018: support cover-glass gain compensation via DT

[Andy Shevchenko]

On Thu, Jun 04, 2026 at 12:06:17PM +0200, Herman van Hazendonk wrote:
> Boards that mount the ISL29018 behind tinted or coated cover glass
> experience optical loss that effectively reduces the sensor's apparent
> sensitivity.  The existing in_illuminance0_calibscale sysfs attribute
> can correct for this at runtime, but firmware knows the loss factor at
> design time and there is no way to seed it without a userspace helper.
> 
> Add support for an optional "isil,cover-comp-gain" device-tree property
> that initialises calibscale at probe time.  If the property is present
> but cannot be read, probe returns an error via dev_err_probe() so the
> root cause is visible in the log.  If absent, calibscale defaults to 1
> (unity gain, matching the previous behaviour).  Userspace can still
> override the value at runtime through the sysfs attribute.
> 
> The approach follows the precedent set by the TSL2563 driver.

...

>  	struct iio_dev *indio_dev;
>  	const void *ddata = NULL;
>  	const char *name;
> +	struct device *dev;
>  	int dev_id;
>  	int err;
>  

> +	dev = &client->dev;

Make this go together with the definition.

	struct device *dev = &client->dev;


...

Use something like

	const char *propname;
	...
	propname = "isil,cover-comp-gain";


> +	if (device_property_present(dev, "isil,cover-comp-gain")) {
> +		err = device_property_read_u32(dev, "isil,cover-comp-gain",
> +					       &chip->calibscale);
> +		if (err)
> +			return dev_err_probe(dev, err,
> +					     "invalid isil,cover-comp-gain\n");

And make these three one-liners.

> +	} else {
> +		chip->calibscale = 1;
> +	}

-- 
With Best Regards,
Andy Shevchenko