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=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 DD620C433E0 for ; Thu, 18 Jun 2020 02:05:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B058C20B1F for ; Thu, 18 Jun 2020 02:05:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592445927; bh=AzvA2jNCztywhn4mIUKL/vqnsmMTPze69mXwwfGUqIg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=U3oaobG8N/NYWcwds0qYWeUXibOyNLWKRgRI3biJKnYowhCJ/TAgFYPfnFv7nKlun wkZhL7q6kbYv4/E205NTvRihhJl+ntwUtGzCOAKd8NlA20J/DPkLKZRw8KTgjXOS94 8BIwPTiiRmbmpli9jx3Vw6sUQGKKzPgE3WJOtdc4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730822AbgFRBWq (ORCPT ); Wed, 17 Jun 2020 21:22:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:55872 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730815AbgFRBWn (ORCPT ); Wed, 17 Jun 2020 21:22:43 -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 3673120B1F; Thu, 18 Jun 2020 01:22:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592443362; bh=AzvA2jNCztywhn4mIUKL/vqnsmMTPze69mXwwfGUqIg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zKWvUr5jSasvG43ZjL8xVC3DxAnjrratRk2CCNwmCGGXzenG8odBqjif77RNEkCXi Lk9cFHeR8UaItpH0d4kk4dn4CGw2GCY+9+GJaDoq3G7wsMFvcE7NUIfccXNntxjL0a Er3DU3geTbwI009VzPXcoWpTlXA4EFo/OPPkJOzg= 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 4.19 019/172] iio: bmp280: fix compensation of humidity Date: Wed, 17 Jun 2020 21:19:45 -0400 Message-Id: <20200618012218.607130-19-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200618012218.607130-1-sashal@kernel.org> References: <20200618012218.607130-1-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 d47922a1d0f3..074f6f865008 100644 --- a/drivers/iio/pressure/bmp280-core.c +++ b/drivers/iio/pressure/bmp280-core.c @@ -261,6 +261,8 @@ 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