From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BFDE3C433E2 for ; Thu, 18 Jun 2020 01:09:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9F3CE21D79 for ; Thu, 18 Jun 2020 01:09:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592442544; bh=KV/4TVQazgEth8uM7noTCOHjy48wFXUisUo/higDEX0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=B1z5xdH6OrnHWQ6fYEc69KuxaglRgcOHpwAGrQ6ftWrBaioeaaCtqL6zBKzfpfqRI IzIY9Qwf1d31LYiwanncPe185MO7SxyFr2CRI6xRPqHDCgbQTpUWxfvxDTLEp/DcVh JzhG/BnyRLe+Xz7tKg1TGDfS7JFB4mMcRswFStbA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728023AbgFRBJD (ORCPT ); Wed, 17 Jun 2020 21:09:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:34842 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727945AbgFRBIv (ORCPT ); Wed, 17 Jun 2020 21:08:51 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A123221D7B; Thu, 18 Jun 2020 01:08:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592442531; bh=KV/4TVQazgEth8uM7noTCOHjy48wFXUisUo/higDEX0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zTAVFta6W9dakk5clWe++8TQPscxL9TSiwHCJDhKQpKuSHDFc1YJ8bOH/oXy6lZh+ IuAATbStTRuzvvwBQbU2CAZ09nD46QZJVYfs8JDIwQjMLL8FeG6d3xY19Tf6ZaDTwv d+VrPolV/TzP2mEDn+qBECFZ1Ta5+ImaW/PwWo8g= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Andreas Klinger , Jonathan Cameron , Sasha Levin , linux-iio@vger.kernel.org Subject: [PATCH AUTOSEL 5.7 034/388] iio: bmp280: fix compensation of humidity Date: Wed, 17 Jun 2020 21:02:11 -0400 Message-Id: <20200618010805.600873-34-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200618010805.600873-1-sashal@kernel.org> References: <20200618010805.600873-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andreas Klinger [ Upstream commit dee2dabc0e4115b80945fe2c91603e634f4b4686 ] Limit the output of humidity compensation to the range between 0 and 100 percent. Depending on the calibration parameters of the individual sensor it happens, that a humidity above 100 percent or below 0 percent is calculated, which don't make sense in terms of relative humidity. Add a clamp to the compensation formula as described in the datasheet of the sensor in chapter 4.2.3. Although this clamp is documented, it was never in the driver of the kernel. It depends on the circumstances (calibration parameters, temperature, humidity) if one can see a value above 100 percent without the clamp. The writer of this patch was working with this type of sensor without noting this error. So it seems to be a rare event when this bug occures. Signed-off-by: Andreas Klinger Signed-off-by: Jonathan Cameron Signed-off-by: Sasha Levin --- drivers/iio/pressure/bmp280-core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c index 2540e7c2358c..973264a088f9 100644 --- a/drivers/iio/pressure/bmp280-core.c +++ b/drivers/iio/pressure/bmp280-core.c @@ -271,6 +271,8 @@ static u32 bmp280_compensate_humidity(struct bmp280_data *data, + (s32)2097152) * calib->H2 + 8192) >> 14); var -= ((((var >> 15) * (var >> 15)) >> 7) * (s32)calib->H1) >> 4; + var = clamp_val(var, 0, 419430400); + return var >> 12; }; -- 2.25.1