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=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 EE806C433E0 for ; Tue, 23 Jun 2020 20:03:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C23A520CC7 for ; Tue, 23 Jun 2020 20:03:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592942639; bh=CrgVa/Gc9vKnKaRjzNJoH5yqlCiMSJw0IgPSlPn42iM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=jB+mefhQTGcVziuLI7y0CAgxR3fFurvS8zTfaFOoi3XCvSPHcfC0occf0KYTHte9d WdyMW4BPFMWrYR/cz8EnPblhXp0QMakek9RYk5hIXcB73LO2Cp4o+TAq3tUOpO9L7q Y2q2cFczqO7VBWh2DgfaJykW+NQqyBlS9qWqzfd0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387641AbgFWUD5 (ORCPT ); Tue, 23 Jun 2020 16:03:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:41780 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388111AbgFWUDu (ORCPT ); Tue, 23 Jun 2020 16:03:50 -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 7D49B20EDD; Tue, 23 Jun 2020 20:03:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592942630; bh=CrgVa/Gc9vKnKaRjzNJoH5yqlCiMSJw0IgPSlPn42iM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EggLVt0tyOUrFxzbtIYPUFyWlMSmOC5SX1363+2tLQRzaFvg3Dj2dmWXKbTHlMo5N 0oxLoYGcIQkWEAvxb/7WG3RXje6vLfFqL4Wg77iFWIMn3JgFIY3g0i6inb2EQlDHyl BcQji47Hq6UZ3pSPnICzjij7DNBLIXiWAiQMxt+s= 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 5.7 033/477] iio: bmp280: fix compensation of humidity Date: Tue, 23 Jun 2020 21:50:30 +0200 Message-Id: <20200623195409.164817493@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200623195407.572062007@linuxfoundation.org> References: <20200623195407.572062007@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 2540e7c2358c1..973264a088f98 100644 --- a/drivers/iio/pressure/bmp280-core.c +++ b/drivers/iio/pressure/bmp280-core.c @@ -271,6 +271,8 @@ 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