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

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Message-Id: <1cee45bfc3fa2ab59dcc17242fb52468035360a1.1646743982.git.hns@goldelico.com>
Date:   Tue,  8 Mar 2022 13:53:03 +0100
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Jonathan Cameron <jic23@...nel.org>,
        Colin Ian King <colin.king@...el.com>,
        Sergiu Cuciurean <sergiu.cuciurean@...log.com>,
        Julia Lawall <Julia.Lawall@...ia.fr>,
        "H. Nikolaus Schaller" <hns@...delico.com>
Cc:     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: [PATCH] iio: palmas: shut up warning about calibration mismatch (due to noise)

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>
---
 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;
 	}
 
-- 
2.33.0