From nobody Fri Oct 3 12:39:19 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ABBFA2D5956; Mon, 1 Sep 2025 17:52:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756749136; cv=none; b=d8tXaUtA8pn4vG2XNbo2ckcEoiHRw05mT16l4XIjMpxjg+REW4s+feP8kfTapKMjx11ToFpKzTSr9c0vFiMg0PTH7hKR6hQZLimP2Jad+Nx5HMLeXTYnl5ZEqqYvtBrnhs6zKxtN6Pdmf25ijVjMs/yhFMIdgqBWzXsseuRYmhA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756749136; c=relaxed/simple; bh=KGUQ8nQF7EJ4Z0xNB7nmmTX6/F3u0TQy3BLAfygaiNc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=DeJiYoCcmt27OCd6q2rjQQoa5nxFaGb4baRBlziWAMRz6gadHkvyfaAkcxsBbjZw+WK/NlEuNMt4nCBHE8yMs0uDKlv+zKqOpYJTpH10SOiEfhAJuSkXQN19LBbwKAGpMHXzrl1BVhK7bfyW3wiyasTs+CeUN2vACjmlnf772iI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pcwTUgTw; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="pcwTUgTw" Received: by smtp.kernel.org (Postfix) with ESMTPS id 412FAC4CEF1; Mon, 1 Sep 2025 17:52:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756749136; bh=KGUQ8nQF7EJ4Z0xNB7nmmTX6/F3u0TQy3BLAfygaiNc=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=pcwTUgTw8hsLWJ4VULlbahG2i5o4oHlxJvRPArpMjOtjdEc9+h90fqVrbKMf+ULVv ZMihZgRmpd19OEHlHLXUdqNP2uPbNGuHLLXX/w87eOX7r1q8lv4EAWvpWH91tKo6We 4MgDTFWbeWVTMzdA7uVv2Wot4JLtse6Qeb9WRhUZKs9OocUHvFD4XtTa1pNgWaP5F/ TlGoJChBVAvRLxefQAtCjPD7M1VWgyY43gZcTe3EyOwcOh5+qDB75AdWRtBwt9djzD HqFE0sT9n7tXGy/JG7G9C9GZn+XjSQq1Jr7P0XIXOg1ek+QtKQ0rD7mFkmCdizSDy0 m99CTabG9GN7Q== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 34E7FCA1009; Mon, 1 Sep 2025 17:52:16 +0000 (UTC) From: Dimitri Fedrau via B4 Relay Date: Mon, 01 Sep 2025 19:51:59 +0200 Subject: [PATCH v2 2/2] iio: humditiy: hdc3020: fix units for thresholds and hysteresis Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250901-hdc3020-units-fix-v2-2-082038a15917@liebherr.com> References: <20250901-hdc3020-units-fix-v2-0-082038a15917@liebherr.com> In-Reply-To: <20250901-hdc3020-units-fix-v2-0-082038a15917@liebherr.com> To: Javier Carrasco , Li peiyu <579lpy@gmail.com>, Jonathan Cameron , David Lechner , =?utf-8?q?Nuno_S=C3=A1?= , Andy Shevchenko , Dimitri Fedrau Cc: Jonathan Cameron , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Dimitri Fedrau , Chris Lesiak X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1756749134; l=8084; i=dimitri.fedrau@liebherr.com; s=20241202; h=from:subject:message-id; bh=Lts1E4+aGdVaGdbWwUlD34fCkeMYPA8ydfn3I+j98D8=; b=NCeJXucYKgARl2VNR99RQw/P3OtpJ7NSmm9NEqEMLrW2if5AjoI/JKk47w16421rj1PRF9Lz9 x63X8bSaMTeAr/EsVdkhLj4sLVO3oFl2JXWmz8Om2JDuWZUiPeeZWM6 X-Developer-Key: i=dimitri.fedrau@liebherr.com; a=ed25519; pk=rT653x09JSQvotxIqQl4/XiI4AOiBZrdOGvxDUbb5m8= X-Endpoint-Received: by B4 Relay for dimitri.fedrau@liebherr.com/20241202 with auth_id=290 X-Original-From: Dimitri Fedrau Reply-To: dimitri.fedrau@liebherr.com From: Dimitri Fedrau According to the ABI the units after application of scale and offset are milli degree celsius for temperature thresholds and milli percent for relative humidity thresholds. Currently the resulting units are degree celsius for temperature thresholds and hysteresis and percent for relative humidity thresholds and hysteresis. Change scale factor to fix this issue. Fixes: 3ad0e7e5f0cb ("iio: humidity: hdc3020: add threshold events support") Reported-by: Chris Lesiak Signed-off-by: Dimitri Fedrau --- drivers/iio/humidity/hdc3020.c | 69 +++++++++++++++++++++++++-------------= ---- 1 file changed, 41 insertions(+), 28 deletions(-) diff --git a/drivers/iio/humidity/hdc3020.c b/drivers/iio/humidity/hdc3020.c index 8aa567d9aded9cab461f1f905b6b5ada721ba2f0..deb19e0291f7f820c5f8760fbf0= 682379ab5f34b 100644 --- a/drivers/iio/humidity/hdc3020.c +++ b/drivers/iio/humidity/hdc3020.c @@ -72,6 +72,13 @@ #define HDC3020_MAX_TEMP_HYST_MICRO 164748607 #define HDC3020_MAX_HUM_MICRO 99220264 =20 +/* + * In order to avoid overflows when returning thresholds and hysteresis va= lues, + * the fraction of these is set to 13107, also the datasheet refers to 655= 35 + * this is not enough to prevent overflows. Dividing this value by 5 fixes= this. + */ +#define HDC3020_THRESH_FRACTION (65535 / 5) + struct hdc3020_data { struct i2c_client *client; struct gpio_desc *reset_gpio; @@ -376,15 +383,16 @@ static int hdc3020_thresh_get_temp(u16 thresh) int temp; =20 /* - * Get the temperature threshold from 9 LSBs, shift them to get - * the truncated temperature threshold representation and - * calculate the threshold according to the formula in the - * datasheet. Result is degree celsius scaled by 65535. + * Get the temperature threshold from 9 LSBs, shift them to get the + * truncated temperature threshold representation and calculate the + * threshold according to the formula in the datasheet and additionally + * scale by HDC3020_THRESH_FRACTION to avoid precision loss when + * calculating threshold and hysteresis values. */ temp =3D FIELD_GET(HDC3020_THRESH_TEMP_MASK, thresh) << HDC3020_THRESH_TEMP_TRUNC_SHIFT; =20 - return -2949075 + (175 * temp); + return -589815 + (35 * temp); } =20 static int hdc3020_thresh_get_hum(u16 thresh) @@ -394,13 +402,14 @@ static int hdc3020_thresh_get_hum(u16 thresh) /* * Get the humidity threshold from 7 MSBs, shift them to get the * truncated humidity threshold representation and calculate the - * threshold according to the formula in the datasheet. Result is - * percent scaled by 65535. + * threshold according to the formula in the datasheet and additionally + * scale by HDC3020_THRESH_FRACTION to avoid precision loss when + * calculating threshold and hysteresis values. */ hum =3D FIELD_GET(HDC3020_THRESH_HUM_MASK, thresh) << HDC3020_THRESH_HUM_TRUNC_SHIFT; =20 - return hum * 100; + return hum * 20; } =20 static u16 hdc3020_thresh_set_temp(int s_temp, u16 curr_thresh) @@ -455,8 +464,8 @@ int hdc3020_thresh_clr(s64 s_thresh, s64 s_hyst, enum i= io_event_direction dir) else s_clr =3D s_thresh + s_hyst; =20 - /* Divide by 65535 to get units of micro */ - return div_s64(s_clr, 65535); + /* Divide by HDC3020_THRESH_FRACTION to get units of micro */ + return div_s64(s_clr, HDC3020_THRESH_FRACTION); } =20 static int _hdc3020_write_thresh(struct hdc3020_data *data, u16 reg, u16 v= al) @@ -507,7 +516,7 @@ static int hdc3020_write_thresh(struct iio_dev *indio_d= ev, =20 clr =3D ret; /* Scale value to include decimal part into calculations */ - s_val =3D (val < 0) ? (val * 1000000 - val2) : (val * 1000000 + val2); + s_val =3D (val < 0) ? (val * 1000 - val2) : (val * 1000 + val2); switch (chan->type) { case IIO_TEMP: switch (info) { @@ -523,7 +532,8 @@ static int hdc3020_write_thresh(struct iio_dev *indio_d= ev, /* Calculate old hysteresis */ s_thresh =3D (s64)hdc3020_thresh_get_temp(thresh) * 1000000; s_clr =3D (s64)hdc3020_thresh_get_temp(clr) * 1000000; - s_hyst =3D div_s64(abs(s_thresh - s_clr), 65535); + s_hyst =3D div_s64(abs(s_thresh - s_clr), + HDC3020_THRESH_FRACTION); /* Set new threshold */ thresh =3D reg_val; /* Set old hysteresis */ @@ -532,16 +542,17 @@ static int hdc3020_write_thresh(struct iio_dev *indio= _dev, case IIO_EV_INFO_HYSTERESIS: /* * Function hdc3020_thresh_get_temp returns temperature - * in degree celsius scaled by 65535. Scale by 1000000 - * to be able to subtract scaled hysteresis value. + * in degree celsius scaled by HDC3020_THRESH_FRACTION. + * Scale by 1000000 to be able to subtract scaled + * hysteresis value. */ s_thresh =3D (s64)hdc3020_thresh_get_temp(thresh) * 1000000; /* * Units of s_val are in micro degree celsius, scale by - * 65535 to get same units as s_thresh. + * HDC3020_THRESH_FRACTION to get same units as s_thresh. */ s_val =3D min(abs(s_val), HDC3020_MAX_TEMP_HYST_MICRO); - s_hyst =3D (s64)s_val * 65535; + s_hyst =3D (s64)s_val * HDC3020_THRESH_FRACTION; s_clr =3D hdc3020_thresh_clr(s_thresh, s_hyst, dir); s_clr =3D max(s_clr, HDC3020_MIN_TEMP_MICRO); s_clr =3D min(s_clr, HDC3020_MAX_TEMP_MICRO); @@ -565,7 +576,8 @@ static int hdc3020_write_thresh(struct iio_dev *indio_d= ev, /* Calculate old hysteresis */ s_thresh =3D (s64)hdc3020_thresh_get_hum(thresh) * 1000000; s_clr =3D (s64)hdc3020_thresh_get_hum(clr) * 1000000; - s_hyst =3D div_s64(abs(s_thresh - s_clr), 65535); + s_hyst =3D div_s64(abs(s_thresh - s_clr), + HDC3020_THRESH_FRACTION); /* Set new threshold */ thresh =3D reg_val; /* Try to set old hysteresis */ @@ -574,15 +586,16 @@ static int hdc3020_write_thresh(struct iio_dev *indio= _dev, case IIO_EV_INFO_HYSTERESIS: /* * Function hdc3020_thresh_get_hum returns relative - * humidity in percent scaled by 65535. Scale by 1000000 - * to be able to subtract scaled hysteresis value. + * humidity in percent scaled by HDC3020_THRESH_FRACTION. + * Scale by 1000000 to be able to subtract scaled + * hysteresis value. */ s_thresh =3D (s64)hdc3020_thresh_get_hum(thresh) * 1000000; /* - * Units of s_val are in micro percent, scale by 65535 - * to get same units as s_thresh. + * Units of s_val are in micro percent, scale by + * HDC3020_THRESH_FRACTION to get same units as s_thresh. */ - s_hyst =3D (s64)s_val * 65535; + s_hyst =3D (s64)s_val * HDC3020_THRESH_FRACTION; s_clr =3D hdc3020_thresh_clr(s_thresh, s_hyst, dir); s_clr =3D max(s_clr, 0); s_clr =3D min(s_clr, HDC3020_MAX_HUM_MICRO); @@ -630,7 +643,7 @@ static int hdc3020_read_thresh(struct iio_dev *indio_de= v, thresh =3D hdc3020_thresh_get_temp(ret); switch (info) { case IIO_EV_INFO_VALUE: - *val =3D thresh; + *val =3D thresh * MILLI; break; case IIO_EV_INFO_HYSTERESIS: ret =3D hdc3020_read_be16(data, reg_clr); @@ -638,18 +651,18 @@ static int hdc3020_read_thresh(struct iio_dev *indio_= dev, return ret; =20 clr =3D hdc3020_thresh_get_temp(ret); - *val =3D abs(thresh - clr); + *val =3D abs(thresh - clr) * MILLI; break; default: return -EOPNOTSUPP; } - *val2 =3D 65535; + *val2 =3D HDC3020_THRESH_FRACTION; return IIO_VAL_FRACTIONAL; case IIO_HUMIDITYRELATIVE: thresh =3D hdc3020_thresh_get_hum(ret); switch (info) { case IIO_EV_INFO_VALUE: - *val =3D thresh; + *val =3D thresh * MILLI; break; case IIO_EV_INFO_HYSTERESIS: ret =3D hdc3020_read_be16(data, reg_clr); @@ -657,12 +670,12 @@ static int hdc3020_read_thresh(struct iio_dev *indio_= dev, return ret; =20 clr =3D hdc3020_thresh_get_hum(ret); - *val =3D abs(thresh - clr); + *val =3D abs(thresh - clr) * MILLI; break; default: return -EOPNOTSUPP; } - *val2 =3D 65535; + *val2 =3D HDC3020_THRESH_FRACTION; return IIO_VAL_FRACTIONAL; default: return -EOPNOTSUPP; --=20 2.39.5