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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 8D0A4C43219 for ; Tue, 30 Apr 2019 12:20:18 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 589582075E for ; Tue, 30 Apr 2019 12:20:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="m4IwKzTW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 589582075E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=tkos.co.il Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date: In-reply-to:Subject:To:From:References:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=ZbGs6x+EZjbYRDdruMN7bHMKGmtspC7MG62HkHk4MZE=; b=m4IwKzTWdniDyt2G8/tqxl2Qmo bd7IkEJVGqTwmvwm/lqoH7plqNAGN0l62frIy7ZM316uh2aNBbv+iPdzFK/hEheH0ixgO6vI9bQHW irAOpqoXO389hwVBCiD7/B1xwgoolcTe8/u8QvK6auEkrH/X1D/3hIv2/jNXtIeGjJcfFi7KexqGk kglatIjU/xSY2z+hodNIJ/PV/z957s+rUmi5UcgT8Knfd5LZToevBeiTFpkRF5EXTX9c81q1Knu5H iVzvg6RJfQrE6Y4Ac2Siw3XWoUEAP148iGvef3d1JklsOGoUBaEKg2HjYQ0tfLKEXzUmXuhy4jpBL S/R4wKhA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hLRk7-0002Yc-8N; Tue, 30 Apr 2019 12:20:15 +0000 Received: from guitar.tcltek.co.il ([192.115.133.116] helo=mx.tkos.co.il) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hLRk3-0002Xu-9a for linux-arm-kernel@lists.infradead.org; Tue, 30 Apr 2019 12:20:12 +0000 Received: from tarshish (unknown [10.0.8.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx.tkos.co.il (Postfix) with ESMTPS id 3EF1744028D; Tue, 30 Apr 2019 15:20:09 +0300 (IDT) References: <20190430093212.28425-1-alexandre.belloni@bootlin.com> <20190430093212.28425-2-alexandre.belloni@bootlin.com> <877ebbu3lz.fsf@tarshish> <20190430114702.GD11339@piout.net> User-agent: mu4e 1.0; emacs 26.1 From: Baruch Siach To: Alexandre Belloni Subject: Re: [PATCH 2/4] rtc: digicolor: set range In-reply-to: <20190430114702.GD11339@piout.net> Date: Tue, 30 Apr 2019 15:20:08 +0300 Message-ID: <875zqvu1l3.fsf@tarshish> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190430_052011_578656_88C86374 X-CRM114-Status: GOOD ( 18.79 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Alexandre, On Tue, Apr 30 2019, Alexandre Belloni wrote: > On 30/04/2019 14:36:24+0300, Baruch Siach wrote: >> Hi Alexandre, >> >> On Tue, Apr 30 2019, Alexandre Belloni wrote: >> >> > While the range of REFERENCE + TIME is actually 33 bits, the counter >> > itself (TIME) is a 32-bits seconds counter. >> > >> > Signed-off-by: Alexandre Belloni >> > --- >> > drivers/rtc/rtc-digicolor.c | 1 + >> > 1 file changed, 1 insertion(+) >> > >> > diff --git a/drivers/rtc/rtc-digicolor.c b/drivers/rtc/rtc-digicolor.c >> > index 5bb14c56bc9a..e6e16aaac254 100644 >> > --- a/drivers/rtc/rtc-digicolor.c >> > +++ b/drivers/rtc/rtc-digicolor.c >> > @@ -206,6 +206,7 @@ static int __init dc_rtc_probe(struct platform_device *pdev) >> > platform_set_drvdata(pdev, rtc); >> > >> > rtc->rtc_dev->ops = &dc_rtc_ops; >> > + rtc->rtc_dev->range_max = U32_MAX; >> >> Where can I find documentation on the meaning and usage of the range_max >> value? I could not find anything in the kernel source. > > It should be set to the maximum UNIX timestamp the RTC can be set to > while keeping range_min to range_max contiguous. > > In the digicolor case, you could go up to 8589934590 (Wed Mar 16 > 12:56:30 UTC 2242) but the driver only writes DC_RTC_REFERENCE and I'm > not sure it can also update DC_RTC_TIME safely. DC_RTC_TIME resets to zero whenever dc_rtc_write writes CMD_RESET to the DC_RTC_CONTROL register. DC_RTC_REFERENCE keeps the value that dc_rtc_write stores there. So the driver will return values larger than U32_MAX if you happen to cross this point in time between dc_rtc_write and dc_rtc_read. But you can't store a value larger than U32_MAX in DC_RTC_REFERENCE. Will the core RTC code handle the U32_MAX cross correctly? baruch -- http://baruch.siach.name/blog/ ~. .~ Tk Open Systems =}------------------------------------------------ooO--U--Ooo------------{= - baruch@tkos.co.il - tel: +972.52.368.4656, http://www.tkos.co.il - _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel