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=-10.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 63FDCC433DF for ; Tue, 23 Jun 2020 21:22:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3EDB220738 for ; Tue, 23 Jun 2020 21:22:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592947346; bh=yOcyIKRlgo1XsxFKyqlJS8YrE8ueduBqHevWzvDAzRM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=j769NuS/udBEBLMzr2tPV1OSdwqka3+yuCRWgU4RTM2N+JGHuQooqF5bONhvNS0d9 0ty6pD0CdrAhF3JNOTv3SS1/p9hNXCiDQcAuk+03ZO/+OakY2z9KaGIt8Xm4r8biPX GkMrf6qqlHi2L3zmoilvgPIRONUse/LQO6jsltnk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389585AbgFWUWJ (ORCPT ); Tue, 23 Jun 2020 16:22:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:39898 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389561AbgFWUWE (ORCPT ); Tue, 23 Jun 2020 16:22:04 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B8BF42064B; Tue, 23 Jun 2020 20:22:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592943724; bh=yOcyIKRlgo1XsxFKyqlJS8YrE8ueduBqHevWzvDAzRM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tpkPvy4df7RqPajV1+wrF/q4HTHHwCJ/cPxex1vViJgb0uLCDHtpCtzigPqVKED0Q b3pDHkC0qCPC3I46LxT0temiyyqk6TZeCU9PeXJuYF2ylCND2hxrjhCuj9MdgxSaPk MbpSYiZnyi5qL1OPzDzawYeOXxocqyR+y8ExSJi4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andreas Klinger , Jonathan Cameron , Sasha Levin Subject: [PATCH 5.4 025/314] iio: bmp280: fix compensation of humidity Date: Tue, 23 Jun 2020 21:53:40 +0200 Message-Id: <20200623195340.000616154@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200623195338.770401005@linuxfoundation.org> References: <20200623195338.770401005@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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 084a1d56cc2f0..0a95afaa48fe6 100644 --- a/drivers/iio/pressure/bmp280-core.c +++ b/drivers/iio/pressure/bmp280-core.c @@ -264,6 +264,8 @@ 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