linux-kernel - Re: [PATCH v2 04/12] iio: adc: ad7192: handle zero Avdd regulator value as error

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Message-ID: <20210511151323.30832207@jic23-huawei>
Date:   Tue, 11 May 2021 15:13:23 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Alexandru Ardelean <aardelean@...iqon.com>
Cc:     linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jonathan.Cameron@...wei.com, alexandru.tachici@...log.com,
        linux@...iqon.com
Subject: Re: [PATCH v2 04/12] iio: adc: ad7192: handle zero Avdd regulator
 value as error

On Tue, 11 May 2021 10:18:23 +0300
Alexandru Ardelean <aardelean@...iqon.com> wrote:

> This change fixes a corner-case, where the returned voltage is actually
> zero. This is also what patch ab0afa65bbc7 ("staging: iio: adc: ad7192:
> fail probe on get_voltage") was trying to do.
> 
> But as Jonathan pointed out, a zero-value would signal that the probe has
> succeeded, putting the driver is a semi-initialized state.
> 
> Fixes: ab0afa65bbc7 ("staging: iio: adc: ad7192: fail probe on get_voltage")
> Cc: Alexandru Tachici <alexandru.tachici@...log.com>
> Signed-off-by: Alexandru Ardelean <aardelean@...iqon.com>

Given that voltage_uv == 1 would result in a situation no worse than
for voltage_uv == 0 perhaps we should just change the following condition to

if (voltage_uv >= 0)  ?

Jonathan

> ---
>  drivers/iio/adc/ad7192.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/iio/adc/ad7192.c b/drivers/iio/adc/ad7192.c
> index d3be67aa0522..79df54e0dc96 100644
> --- a/drivers/iio/adc/ad7192.c
> +++ b/drivers/iio/adc/ad7192.c
> @@ -950,6 +950,11 @@ static int ad7192_probe(struct spi_device *spi)
>  	}
>  
>  	voltage_uv = regulator_get_voltage(st->avdd);
> +	if (voltage_uv == 0) {
> +		ret = -EINVAL;
> +		dev_err(&spi->dev, "Zero value provided for AVdd supply\n");
> +		goto error_disable_avdd;
> +	}
>  
>  	if (voltage_uv > 0) {
>  		st->int_vref_mv = voltage_uv / 1000;