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=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,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 C0913C433E9 for ; Tue, 2 Mar 2021 00:36:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 528A660C40 for ; Tue, 2 Mar 2021 00:36:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245162AbhCBA1U (ORCPT ); Mon, 1 Mar 2021 19:27:20 -0500 Received: from mail.kernel.org ([198.145.29.99]:43154 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240005AbhCAS2R (ORCPT ); Mon, 1 Mar 2021 13:28:17 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0FA0565147; Mon, 1 Mar 2021 17:04:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614618295; bh=3Mc4cA98KQnMxG8KFclS80cMHAKi4ZGfXjeSx4pzjQk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lCKmMI0yDYjqpGIz/R41iZiC/honUh3AB9akOM29U2aWCYKTKenS5v7vDQx1lGrEp iTIaCXZaPyOzmyPfVg9iCKTQ71DuSCYkEPDzJezolW9aGS9RlPpZ3olGdbTiJMSH6Z FN8YQMaqVSU2uFJ+FyO0aNIYv7owkfuWRYxzmsvc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Pawe=C5=82=20Marciniak?= , Ivan Zaentsev Subject: [PATCH 5.10 008/663] w1: w1_therm: Fix conversion result for negative temperatures Date: Mon, 1 Mar 2021 17:04:16 +0100 Message-Id: <20210301161142.187971446@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210301161141.760350206@linuxfoundation.org> References: <20210301161141.760350206@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ivan Zaentsev commit 2f6055c26f1913763eabc66c7c27d0693561e966 upstream. DS18B20 device driver returns an incorrect value for negative temperatures due to a missing sign-extension in w1_DS18B20_convert_temp(). Fix by using s16 temperature value when converting to int. Fixes: 9ace0b4dab1c (w1: w1_therm: Add support for GXCAS GX20MH01 device.) Cc: stable Reported-by: Paweł Marciniak Signed-off-by: Ivan Zaentsev Link: https://lore.kernel.org/r/20210121093021.224764-1-ivan.zaentsev@wirenboard.ru Signed-off-by: Greg Kroah-Hartman --- drivers/w1/slaves/w1_therm.c | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-) --- a/drivers/w1/slaves/w1_therm.c +++ b/drivers/w1/slaves/w1_therm.c @@ -667,28 +667,24 @@ static inline int w1_DS18B20_get_resolut */ static inline int w1_DS18B20_convert_temp(u8 rom[9]) { - int t; - u32 bv; + u16 bv; + s16 t; + + /* Signed 16-bit value to unsigned, cpu order */ + bv = le16_to_cpup((__le16 *)rom); /* Config register bit R2 = 1 - GX20MH01 in 13 or 14 bit resolution mode */ if (rom[4] & 0x80) { - /* Signed 16-bit value to unsigned, cpu order */ - bv = le16_to_cpup((__le16 *)rom); - /* Insert two temperature bits from config register */ /* Avoid arithmetic shift of signed value */ bv = (bv << 2) | (rom[4] & 3); - - t = (int) sign_extend32(bv, 17); /* Degrees, lowest bit is 2^-6 */ - return (t*1000)/64; /* Millidegrees */ + t = (s16) bv; /* Degrees, lowest bit is 2^-6 */ + return (int)t * 1000 / 64; /* Sign-extend to int; millidegrees */ } - - t = (int)le16_to_cpup((__le16 *)rom); - return t*1000/16; + t = (s16)bv; /* Degrees, lowest bit is 2^-4 */ + return (int)t * 1000 / 16; /* Sign-extend to int; millidegrees */ } - - /** * w1_DS18S20_convert_temp() - temperature computation for DS18S20 * @rom: data read from device RAM (8 data bytes + 1 CRC byte)