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 541C6C433E1 for ; Thu, 18 Jun 2020 01:45:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 295EB221EE for ; Thu, 18 Jun 2020 01:45:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592444751; bh=bZlXP3rtIi7UXa7hqh4nOqVwJDoZtVCqAhWgn6JQ2wE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=kMCuNTaeJdfqkM/lm1Sjkp9ji4W60DSBp7nSbmW4cRkOvupMHJ4EZbFHst4OHEwjj 9EFZFnhZo6FXzJNiAwNg4y2sqSQdvPPq21T7+5tYbEkj9YtALKwh4RjcS64vfRzd/2 /RwsxHiXhRFGMmFAwU6XgUVufmY0/SmAxlF2hhIE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731085AbgFRBpu (ORCPT ); Wed, 17 Jun 2020 21:45:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:37378 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731065AbgFRB2f (ORCPT ); Wed, 17 Jun 2020 21:28:35 -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 374B022200; Thu, 18 Jun 2020 01:28:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592443714; bh=bZlXP3rtIi7UXa7hqh4nOqVwJDoZtVCqAhWgn6JQ2wE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HO0BUrrrEfRzem0ftRa+IOVZSVbTAjvLxVfCRP3xAVZ5Ai8Enh5J7aPZ36TCMtGN0 40Va7S+FsHJuoph2pe840JYrHgo0ogEmEkQ3bZpsFIPIiI1NJmcarHZ/0W3opV64uc yYeVd7dq4QT1Zk652XDH8M6I5qh9iIQBo/ES6T/k= 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 4.9 12/80] iio: bmp280: fix compensation of humidity Date: Wed, 17 Jun 2020 21:27:11 -0400 Message-Id: <20200618012819.609778-12-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200618012819.609778-1-sashal@kernel.org> References: <20200618012819.609778-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@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 36f03fdf4d4f..85b90b5939db 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