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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 8F524C43441 for ; Wed, 14 Nov 2018 09:59:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 535172145D for ; Wed, 14 Nov 2018 09:59:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 535172145D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bootlin.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-rtc-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727598AbeKNUCN (ORCPT ); Wed, 14 Nov 2018 15:02:13 -0500 Received: from mail.bootlin.com ([62.4.15.54]:58613 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727558AbeKNUCN (ORCPT ); Wed, 14 Nov 2018 15:02:13 -0500 Received: by mail.bootlin.com (Postfix, from userid 110) id 241C120D83; Wed, 14 Nov 2018 10:59:39 +0100 (CET) Received: from localhost (242.171.71.37.rev.sfr.net [37.71.171.242]) by mail.bootlin.com (Postfix) with ESMTPSA id EC41320510; Wed, 14 Nov 2018 10:59:28 +0100 (CET) Date: Wed, 14 Nov 2018 10:59:28 +0100 From: Alexandre Belloni To: Marek Szyprowski Cc: linux-rtc@vger.kernel.org, linux-samsung-soc@vger.kernel.org, Alessandro Zummo , Krzysztof Kozlowski , Bartlomiej Zolnierkiewicz Subject: Re: [PATCH] rtc: s3c-rtc: Avoid using broken ALMYEAR register Message-ID: <20181114095928.GW29768@piout.net> References: <20181113113250.15527-1-m.szyprowski@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181113113250.15527-1-m.szyprowski@samsung.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-rtc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org On 13/11/2018 12:32:50+0100, Marek Szyprowski wrote: > (RTC,ALM)YEAR registers of Exynos built-in RTC device contains 3 BCD > characters. s3c-rtc driver uses only 2 lower of them and supports years > from 2000..2099 range. The third BCD value is typically set to 0, but it > looks that handling of it is broken in the hardware. It sometimes > defaults to a random (even non-BCD) value. This is not an issue > for handling RTCYEAR register, because bcd2bin() properly handles only > 8bit values (2 BCD characters, the third one is skipped). The problem > is however with ALMYEAR register and proper RTC alarm operation. When > YEAREN bit is set for the configured alarm, RTC hardware triggers alarm > only when ALMYEAR and RTCYEAR matches. This usually doesn't happen > because of the random noise on the third BCD character. > > Fix this by simply skipping setting ALMYEAR register in alarm > configuration. This workaround fixes broken alarm operation on Exynos > built-in rtc device. My tests revealed that the issue happens on the > following Exynos series: 3250, 4210, 4412, 5250 and 5410. > > Signed-off-by: Marek Szyprowski > --- > drivers/rtc/rtc-s3c.c | 6 ------ > 1 file changed, 6 deletions(-) > Applied, thanks. -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com