From patchwork Tue Jun 23 19:53:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 223500 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=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 13D71C433DF for ; Tue, 23 Jun 2020 20:22:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DB2F02064B for ; Tue, 23 Jun 2020 20:22:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592943727; bh=yOcyIKRlgo1XsxFKyqlJS8YrE8ueduBqHevWzvDAzRM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=L+ntnUzwnC0WyvPG0XeB0pA36TZW5A9STrUEaRUNU0lRpPVcMmKkQHGq3SRN++Udu vxCSOD6HnkV0YHfKwhPhVx2jCHJwb4ioAfzdeGZmMyG1iDp85go59bjU5IV2snnHpB XDaZiGGjcR8euSC1w2zqNqnyH3c8MAg/wZUFTZR0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390121AbgFWUWF (ORCPT ); Tue, 23 Jun 2020 16:22:05 -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 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@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; };