From patchwork Tue Jun 23 19:55:44 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 223275 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 016DEC433DF for ; Tue, 23 Jun 2020 21:08:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C823120663 for ; Tue, 23 Jun 2020 21:07:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592946479; bh=uXUqcb3/5OyWB5KqDbr0UKr9O1qqmmzkYoU7K1W9SoM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=kz5zJd6IMuSkr3Tu4Dngt+abBl8/MKkuLRdjCXSISlOwakSDQkIQ1XEKWa8T/BAAl SVINQNUsBGlnB5+0oV+xK8V//BeT30wtXduVRZWxEJ5o807CJlO4wew0N68JsL4h0U o6OZfyWPeCH7QfKAD29bYuWka49+kjStCuVHZhvA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388343AbgFWVHu (ORCPT ); Tue, 23 Jun 2020 17:07:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:57260 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391652AbgFWUfD (ORCPT ); Tue, 23 Jun 2020 16:35:03 -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 5F2AB2080C; Tue, 23 Jun 2020 20:35:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592944503; bh=uXUqcb3/5OyWB5KqDbr0UKr9O1qqmmzkYoU7K1W9SoM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lM+8vDiHX6LiQxhEnZS1bVG/qVE+tWNZI0mw6zuiKSee+WHOX/KN6DRqYl+HxeaAR UOlybzVaWggad4ra0IwCzN16GVpsKTffkEzF6aP0oXjZ1GhUq07KVkiw0BX7Fm80/O Uet8XzKRmYZLSuOITafxkB1vfg05J14zvKl6lVWc= 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 4.19 016/206] iio: bmp280: fix compensation of humidity Date: Tue, 23 Jun 2020 21:55:44 +0200 Message-Id: <20200623195317.761245881@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200623195316.864547658@linuxfoundation.org> References: <20200623195316.864547658@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 d47922a1d0f37..074f6f865008c 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; };