linux-kernel - Re: [PATCH] iio: palmas: shut up warning about calibration mismatch (due to noise)

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Date:   Sun, 20 Mar 2022 15:52:59 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     "H. Nikolaus Schaller" <hns@...delico.com>
Cc:     Colin Ian King <colin.king@...el.com>,
        Sergiu Cuciurean <sergiu.cuciurean@...log.com>,
        Julia Lawall <Julia.Lawall@...ia.fr>,
        Lars-Peter Clausen <lars@...afoo.de>,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        letux-kernel@...nphoenux.org, kernel@...a-handheld.com,
        linux-omap@...r.kernel.org
Subject: Re: [PATCH] iio: palmas: shut up warning about calibration mismatch
 (due to noise)

On Tue,  8 Mar 2022 13:53:03 +0100
"H. Nikolaus Schaller" <hns@...delico.com> wrote:

> Although technically checking for ADC values below 0 is correct,
> because they are outside of the calibration values, there is usually
> noise which spuriously fills the console log with error messages if
> calculated input voltage gets close to 0V.
> 
> Ignore small negative calculated values, but clamp them to 0.
> 
> Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>
Hi.

Should we treat this as a fix or a cleanup?

I don't mind either way.

Jonathan


> ---
>  drivers/iio/adc/palmas_gpadc.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/palmas_gpadc.c b/drivers/iio/adc/palmas_gpadc.c
> index f9c8385c72d3..bcfa6a7f6cb2 100644
> --- a/drivers/iio/adc/palmas_gpadc.c
> +++ b/drivers/iio/adc/palmas_gpadc.c
> @@ -376,7 +376,8 @@ static int palmas_gpadc_get_calibrated_code(struct palmas_gpadc *adc,
>  					adc->adc_info[adc_chan].gain_error;
>  
>  	if (val < 0) {
> -		dev_err(adc->dev, "Mismatch with calibration\n");
> +		if (val < -10)
> +			dev_err(adc->dev, "Mismatch with calibration var = %d\n", val);
>  		return 0;
>  	}
>