Re: [PATCH 1/5 V2] staging: iio: adc: ad7192: fail probe on get_voltage

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 5 Feb 2020 19:15:07 +0200
Alexandru Tachici <alexandru.tachici@analog.com> wrote:

> This patch makes the ad7192_probe fail in case
> regulator_get_voltage will return an error.
> 
> Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>

There is a subtlety in here we should handle.

> ---
>  drivers/staging/iio/adc/ad7192.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/iio/adc/ad7192.c b/drivers/staging/iio/adc/ad7192.c
> index bf3e2a9cc07f..4780ddf99b13 100644
> --- a/drivers/staging/iio/adc/ad7192.c
> +++ b/drivers/staging/iio/adc/ad7192.c
> @@ -899,10 +899,13 @@ static int ad7192_probe(struct spi_device *spi)
>  
>  	voltage_uv = regulator_get_voltage(st->avdd);
>
I had to dig a bit to check this as it's not documented.
regulator_get_voltage returns negative for error, not 0.
0 typically means the voltage has not been set or has been
explicitly set to 0. 

So if it is set to 0 I suppose we could try setting it as it
might be a variable high precision reference?

Perhaps for now just spitting out an error is the best plan.

  
> -	if (voltage_uv)
> +	if (voltage_uv) {
>  		st->int_vref_mv = voltage_uv / 1000;
> -	else
> +	} else {
> +		ret = voltage_uv;
>  		dev_err(&spi->dev, "Device tree error, reference voltage undefined\n");
> +		goto error_disable_avdd;
> +	}
>  
>  	spi_set_drvdata(spi, indio_dev);
>  	st->devid = spi_get_device_id(spi)->driver_data;
> @@ -957,6 +960,7 @@ static int ad7192_probe(struct spi_device *spi)
>  	ret = iio_device_register(indio_dev);
>  	if (ret < 0)
>  		goto error_disable_clk;
> +
We shouldn't have stray white space changes in a patch making a real change.

Thanks,

Jonathan

>  	return 0;
>  
>  error_disable_clk: