Re: [PATCH v1 1/1] iio: adc: ad7191: Don't check for specific errors when parsing properties

["Nuno Sá" <noname.nuno@gmail.com>]

On Thu, 2026-02-19 at 15:39 +0100, Andy Shevchenko wrote:
> Instead of checking for the specific error codes (that can be considered
> a layering violation to some extent) check for the property existence first
> and then either parse it, or apply a default value.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---

Not really sure how I feel about this one. Checking for specific errors is a very common
pattern and this change just makes it we check for the property presence twice. That said,
this makes it more "future proof" (though I find it very unlikely for ret value o change).

Anyways, even if we choose to go down this route, I don't see much benefit in starting
converting the drivers with the pattern below (which should be a considerable number).

- Nuno Sá
 
>  drivers/iio/adc/ad7191.c | 63 +++++++++++++++++++++-------------------
>  1 file changed, 33 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7191.c b/drivers/iio/adc/ad7191.c
> index d9cd903ffdd2..51ec199fb06f 100644
> --- a/drivers/iio/adc/ad7191.c
> +++ b/drivers/iio/adc/ad7191.c
> @@ -154,27 +154,18 @@ static int ad7191_config_setup(struct iio_dev *indio_dev)
>  	const u32 gain[4] = { 1, 8, 64, 128 };
>  	static u32 scale_buffer[4][2];
>  	int odr_value, odr_index = 0, pga_value, pga_index = 0, i, ret;
> +	const char *propname;
>  	u64 scale_uv;
>  
>  	st->samp_freq_index = 0;
>  	st->scale_index = 0;
>  
> -	ret = device_property_read_u32(dev, "adi,odr-value", &odr_value);
> -	if (ret && ret != -EINVAL)
> -		return dev_err_probe(dev, ret, "Failed to get odr value.\n");
> +	propname = "adi,odr-value";
> +	if (device_property_present(dev, propname)) {
> +		ret = device_property_read_u32(dev, propname, &odr_value);
> +		if (ret)
> +			return dev_err_probe(dev, ret, "Failed to get %s.\n", propname);
>  
> -	if (ret == -EINVAL) {
> -		st->odr_gpios = devm_gpiod_get_array(dev, "odr", GPIOD_OUT_LOW);
> -		if (IS_ERR(st->odr_gpios))
> -			return dev_err_probe(dev, PTR_ERR(st->odr_gpios),
> -					     "Failed to get odr gpios.\n");
> -
> -		if (st->odr_gpios->ndescs != 2)
> -			return dev_err_probe(dev, -EINVAL, "Expected 2 odr gpio pins.\n");
> -
> -		st->samp_freq_avail = samp_freq;
> -		st->samp_freq_avail_size = ARRAY_SIZE(samp_freq);
> -	} else {
>  		for (i = 0; i < ARRAY_SIZE(samp_freq); i++) {
>  			if (odr_value != samp_freq[i])
>  				continue;
> @@ -186,6 +177,17 @@ static int ad7191_config_setup(struct iio_dev *indio_dev)
>  		st->samp_freq_avail_size = 1;
>  
>  		st->odr_gpios = NULL;
> +	} else {
> +		st->odr_gpios = devm_gpiod_get_array(dev, "odr", GPIOD_OUT_LOW);
> +		if (IS_ERR(st->odr_gpios))
> +			return dev_err_probe(dev, PTR_ERR(st->odr_gpios),
> +					     "Failed to get odr gpios.\n");
> +
> +		if (st->odr_gpios->ndescs != 2)
> +			return dev_err_probe(dev, -EINVAL, "Expected 2 odr gpio pins.\n");
> +
> +		st->samp_freq_avail = samp_freq;
> +		st->samp_freq_avail_size = ARRAY_SIZE(samp_freq);
>  	}
>  
>  	mutex_lock(&st->lock);
> @@ -200,22 +202,12 @@ static int ad7191_config_setup(struct iio_dev *indio_dev)
>  
>  	mutex_unlock(&st->lock);
>  
> -	ret = device_property_read_u32(dev, "adi,pga-value", &pga_value);
> -	if (ret && ret != -EINVAL)
> -		return dev_err_probe(dev, ret, "Failed to get pga value.\n");
> +	propname = "adi,pga-value";
> +	if (device_property_present(dev, propname)) {
> +		ret = device_property_read_u32(dev, propname, &pga_value);
> +		if (ret)
> +			return dev_err_probe(dev, ret, "Failed to get %s.\n", propname);
>  
> -	if (ret == -EINVAL) {
> -		st->pga_gpios = devm_gpiod_get_array(dev, "pga", GPIOD_OUT_LOW);
> -		if (IS_ERR(st->pga_gpios))
> -			return dev_err_probe(dev, PTR_ERR(st->pga_gpios),
> -					     "Failed to get pga gpios.\n");
> -
> -		if (st->pga_gpios->ndescs != 2)
> -			return dev_err_probe(dev, -EINVAL, "Expected 2 pga gpio pins.\n");
> -
> -		st->scale_avail = scale_buffer;
> -		st->scale_avail_size = ARRAY_SIZE(scale_buffer);
> -	} else {
>  		for (i = 0; i < ARRAY_SIZE(gain); i++) {
>  			if (pga_value != gain[i])
>  				continue;
> @@ -227,6 +219,17 @@ static int ad7191_config_setup(struct iio_dev *indio_dev)
>  		st->scale_avail_size = 1;
>  
>  		st->pga_gpios = NULL;
> +	} else {
> +		st->pga_gpios = devm_gpiod_get_array(dev, "pga", GPIOD_OUT_LOW);
> +		if (IS_ERR(st->pga_gpios))
> +			return dev_err_probe(dev, PTR_ERR(st->pga_gpios),
> +					     "Failed to get pga gpios.\n");
> +
> +		if (st->pga_gpios->ndescs != 2)
> +			return dev_err_probe(dev, -EINVAL, "Expected 2 pga gpio pins.\n");
> +
> +		st->scale_avail = scale_buffer;
> +		st->scale_avail_size = ARRAY_SIZE(scale_buffer);
>  	}
>  
>  	st->temp_gpio = devm_gpiod_get(dev, "temp", GPIOD_OUT_LOW);