Re: [PATCH v2 4/7] iio: temperature: ltc2983: Use fwnode_property_present() for optional properties

[Jonathan Cameron]

On Thu, 14 May 2026 17:46:51 +0300
Liviu Stan <liviu.stan@xxxxxxxxxx> wrote:

> Checking fwnode_property_read_u32() return value with if (!ret)
> silently swallows meaningful error codes when a property is present
> but malformed. Use fwnode_property_present() first so that absence
> uses the default while a present but unreadable property returns
> a proper error.
> 
 Fixes: f110f3188e5639c81c457b2b831d40dfe3891bdb ("iio: temperature: Add support for LTC2983")
Same again. Not a fix. It's hardening against unexpected errors.

Also, sashiko calls out an issue with n_wires and default value of 0.
The binding says default is 2.


that was always present but is worth a fix potentially:
https://sashiko.dev/#/patchset/20260514144712.64374-1-liviu.stan%40analog.com

> Signed-off-by: Liviu Stan <liviu.stan@xxxxxxxxxx>

> ---
> Changes in v2:
> - New patch.
> 
>  drivers/iio/temperature/ltc2983.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/temperature/ltc2983.c b/drivers/iio/temperature/ltc2983.c
> index f42777c1f3c2..bf435e965c6d 100644
> --- a/drivers/iio/temperature/ltc2983.c
> +++ b/drivers/iio/temperature/ltc2983.c
> @@ -669,8 +669,14 @@ ltc2983_thermocouple_new(const struct fwnode_handle *child, struct ltc2983_data
>  	if (fwnode_property_read_bool(child, "adi,single-ended"))
>  		thermo->sensor_config = LTC2983_THERMOCOUPLE_SGL(1);
>  
> -	ret = fwnode_property_read_u32(child, "adi,sensor-oc-current-microamp", &oc_current);
> -	if (!ret) {
> +	if (fwnode_property_present(child, "adi,sensor-oc-current-microamp")) {
> +		ret = fwnode_property_read_u32(child,
> +					       "adi,sensor-oc-current-microamp",
> +					       &oc_current);
> +		if (ret)
> +			return dev_err_ptr_probe(dev, ret,
> +						 "Failed to read adi,sensor-oc-current-microamp\n");
> +
>  		switch (oc_current) {
>  		case 10:
>  			thermo->sensor_config |=
> @@ -760,8 +766,12 @@ ltc2983_rtd_new(const struct fwnode_handle *child, struct ltc2983_data *st,
>  		return dev_err_ptr_probe(dev, ret,
>  					 "Property reg must be given\n");
>  
> -	ret = fwnode_property_read_u32(child, "adi,number-of-wires", &n_wires);
> -	if (!ret) {
> +	if (fwnode_property_present(child, "adi,number-of-wires")) {
> +		ret = fwnode_property_read_u32(child, "adi,number-of-wires", &n_wires);
> +		if (ret)
> +			return dev_err_ptr_probe(dev, ret,
> +						 "Failed to read adi,number-of-wires\n");
> +
>  		switch (n_wires) {
>  		case 2:
>  			rtd->sensor_config = LTC2983_RTD_N_WIRES(0);