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,USER_AGENT_GIT autolearn=unavailable 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 7425BC433E0 for ; Thu, 18 Jun 2020 01:29:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4C05422210 for ; Thu, 18 Jun 2020 01:29:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592443764; bh=Dwsp6Z4kPZv3ymP53cYNbkg+qUMWFYj7QbpPlxBj5Cs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=OB+YnOMlYp3mtlHJPEzbjwjDrD078H+2AKBiOxgDSmzZcXG77DkeA5o57WmpjMuOz 8qsLd9nHHhZ7zAxgbt+u7SLtIggmk+0Jss0oDpespSCfglzyaCo5rMBNKsWJx37DQS Rht7xjfOqUy42b/jTcWmtkqePYi0KKxUjWNEHAAo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732287AbgFRB3W (ORCPT ); Wed, 17 Jun 2020 21:29:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:33814 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731645AbgFRB0U (ORCPT ); Wed, 17 Jun 2020 21:26:20 -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 1520520897; Thu, 18 Jun 2020 01:26:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592443579; bh=Dwsp6Z4kPZv3ymP53cYNbkg+qUMWFYj7QbpPlxBj5Cs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DVSFdpsrGQnsuVPGigG79qGSjuch6QV8VvrBjfXwFOom3iqVVgB/GQ9JNz0ibs/hf xDSQ8/Un7s2TwYXXvTlZ5mSTCV72lxXcFuIczNQvIJoe/Sz7i5AUnJen+KFKhIVqaR V48Z7GaqHgo6VypVP1i6yZeh46b/n2m09wPqbm3A= 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 4.14 015/108] iio: bmp280: fix compensation of humidity Date: Wed, 17 Jun 2020 21:24:27 -0400 Message-Id: <20200618012600.608744-15-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200618012600.608744-1-sashal@kernel.org> References: <20200618012600.608744-1-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 3204dff34e0a..ae415b4e381a 100644 --- a/drivers/iio/pressure/bmp280-core.c +++ b/drivers/iio/pressure/bmp280-core.c @@ -182,6 +182,8 @@ static u32 bmp280_compensate_humidity(struct bmp280_data *data, + (s32)2097152) * H2 + 8192) >> 14); var -= ((((var >> 15) * (var >> 15)) >> 7) * (s32)H1) >> 4; + var = clamp_val(var, 0, 419430400); + return var >> 12; }; -- 2.25.1