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=-8.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 4C936C04A6B for ; Thu, 9 May 2019 02:20:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1AD322173C for ; Thu, 9 May 2019 02:20:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726082AbfEICUD (ORCPT ); Wed, 8 May 2019 22:20:03 -0400 Received: from www.osadl.org ([62.245.132.105]:60498 "EHLO www.osadl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725842AbfEICUD (ORCPT ); Wed, 8 May 2019 22:20:03 -0400 Received: from debian01.hofrr.at (178.115.242.59.static.drei.at [178.115.242.59]) by www.osadl.org (8.13.8/8.13.8/OSADL-2007092901) with ESMTP id x492JcKg005420; Thu, 9 May 2019 04:19:38 +0200 From: Nicholas Mc Guire To: Alessandro Zummo Cc: Alexandre Belloni , linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org, Nicholas Mc Guire Subject: [PATCH] rtc: ds2404: use hw endiannes variable Date: Thu, 9 May 2019 04:13:55 +0200 Message-Id: <1557368035-6787-1-git-send-email-hofrat@osadl.org> X-Mailer: git-send-email 2.1.4 Sender: linux-rtc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org Converting from hardware to host endiannes was done using reassignment to the same variable which makes sparse unhappy as it can not verify the endiannes handling properly. To allow sparse to verify endiannes handling an explicit __le32 is introduced. Note that this patch does not change the generated binary (x86_64 and ppc64 binary diff). Signed-off-by: Nicholas Mc Guire --- Problem located by an experimental coccinelle script to locate patters that make sparse unhappy (false positives): on little-endian x86_64 sparse complains about: drivers/rtc/rtc-ds2404.c:187:16: warning: cast to restricted __le32 on big-endian ppc64 sparse complains about drivers/rtc/rtc-ds2404.c:187:16: warning: cast to restricted __le32 drivers/rtc/rtc-ds2404.c:187:16: warning: cast to restricted __le32 drivers/rtc/rtc-ds2404.c:187:16: warning: cast to restricted __le32 drivers/rtc/rtc-ds2404.c:187:16: warning: cast to restricted __le32 drivers/rtc/rtc-ds2404.c:187:16: warning: cast to restricted __le32 drivers/rtc/rtc-ds2404.c:187:16: warning: cast to restricted __le32 Patch was compiletested with: x86_64_defconfig + RTC_DRV_DS2404=m ppc64_defconfig + RTC_DRV_DS2404=m in both cases applying the patch has no impact on the generated binary. Patch is against 5.1 (localversion-next is next-20190508) drivers/rtc/rtc-ds2404.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/rtc/rtc-ds2404.c b/drivers/rtc/rtc-ds2404.c index 1e9f429..9df0c44 100644 --- a/drivers/rtc/rtc-ds2404.c +++ b/drivers/rtc/rtc-ds2404.c @@ -182,9 +182,10 @@ static void ds2404_enable_osc(struct device *dev) static int ds2404_read_time(struct device *dev, struct rtc_time *dt) { unsigned long time = 0; + __le32 hw_time = 0; - ds2404_read_memory(dev, 0x203, 4, (u8 *)&time); - time = le32_to_cpu(time); + ds2404_read_memory(dev, 0x203, 4, (u8 *)&hw_time); + time = le32_to_cpu(hw_time); rtc_time64_to_tm(time, dt); return 0; -- 2.1.4