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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 C20AEC4361A for ; Thu, 3 Dec 2020 15:53:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 66C3F207AA for ; Thu, 3 Dec 2020 15:53:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726112AbgLCPxd (ORCPT ); Thu, 3 Dec 2020 10:53:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53078 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726111AbgLCPxc (ORCPT ); Thu, 3 Dec 2020 10:53:32 -0500 Received: from mail-qv1-xf33.google.com (mail-qv1-xf33.google.com [IPv6:2607:f8b0:4864:20::f33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E61C9C061A4F for ; Thu, 3 Dec 2020 07:52:51 -0800 (PST) Received: by mail-qv1-xf33.google.com with SMTP id ec16so1160935qvb.0 for ; Thu, 03 Dec 2020 07:52:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=sza1dnpdO/xRy/URAk8vbDczQ7tTlrJ7/tYshaI+Ua4=; b=hF8ouXjHXZqJp61av+QLd2XwK8d0cLF9jIOk7ianNFJeR0UjYKxMwX59VX43vhHmTc jlNF6uUnkKdDdQXma1bBEMVkSXz+AbXX2me+VSEg4D7CMzllqWgIS4GHBcAae5b9yyrm CYyiQEhg9cOgRRW1PKZzW+5iMUUcXUBqK7kvCMICnbzMviockO55k0BF4lSPgssdipfH 4+THgwN89siTKIGheN4Q9RgyGfjqBV1tNhowV+DzQ8IjKOXix4jrOvrtfBMy8w1b2Zbh L6nyaud1Ki3ou9dv88UzwzdQ2Nxunpc6m1rnqL4YX6wD1AjlTE4tNSb0vFSsHskwUNM4 /PoQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=sza1dnpdO/xRy/URAk8vbDczQ7tTlrJ7/tYshaI+Ua4=; b=klR0+mxH3Uaaj9jJsA6M1Cxgo8VixRjfQohEdPLAfkxCxFY0sWXx74tw3vtRNr+N8a 8VNsyAB69irwzAdvgMH9RmcObhw4VVXs+v9ymJpH0GI80xpaHkX2z2TSuMdQmIJgUzH7 J681KzQgqVRgliNNutIrdP4aKs8A2gOENQSHJahhZoNlRSVvp3B1RbkWKFY1xJyUJTaT +d+ioFU03Ak4SppsqQ+L0PrHBisdR639KQnprXV/ur8cL/Mnpe+29A0sZDIVbmKfpZC9 sVPc99hVGOix9XuWxtAJx5ROfk3z7DuTjQq6uvrxYIZmVfPUR2ds0Ihox99AufCbz/JW dpyg== X-Gm-Message-State: AOAM533cOiUBqFUYWeNBxq8U4OjhycCVptKyh5Q1oxJfOovylzfvRyY9 rJCvGBtx1bewO7JMHSRTdAhT4w== X-Google-Smtp-Source: ABdhPJzJSxMOiKtmp2ZXDGAlZTTKX9jGhy1e+IEpOS4JKBgqHVEZdu2Kh8BIG0+AUiKpZkMVWuNIZw== X-Received: by 2002:a0c:fb07:: with SMTP id c7mr3690951qvp.52.1607010770946; Thu, 03 Dec 2020 07:52:50 -0800 (PST) Received: from ziepe.ca (hlfxns017vw-156-34-48-30.dhcp-dynamic.fibreop.ns.bellaliant.net. [156.34.48.30]) by smtp.gmail.com with ESMTPSA id k27sm1686039qkj.79.2020.12.03.07.52.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Dec 2020 07:52:50 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kkquX-005Wrn-O4; Thu, 03 Dec 2020 11:52:49 -0400 Date: Thu, 3 Dec 2020 11:52:49 -0400 From: Jason Gunthorpe To: Alexandre Belloni Cc: Thomas Gleixner , Miroslav Lichvar , linux-kernel@vger.kernel.org, John Stultz , Prarit Bhargava , Alessandro Zummo , linux-rtc@vger.kernel.org, Peter Zijlstra Subject: Re: [PATCH] rtc: adapt allowed RTC update error Message-ID: <20201203155249.GT5487@ziepe.ca> References: <20201201161224.GF5487@ziepe.ca> <20201201171420.GN1900232@localhost> <20201201173540.GH5487@ziepe.ca> <87mtywe2zu.fsf@nanos.tec.linutronix.de> <20201202162723.GJ5487@ziepe.ca> <87a6uwdnfn.fsf@nanos.tec.linutronix.de> <20201202205418.GN5487@ziepe.ca> <874kl3eu8p.fsf@nanos.tec.linutronix.de> <87zh2vd72z.fsf@nanos.tec.linutronix.de> <20201203021047.GG3544@piout.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201203021047.GG3544@piout.net> Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org On Thu, Dec 03, 2020 at 03:10:47AM +0100, Alexandre Belloni wrote: > IIRC, used in conjunction with rtc_hctosys which also adds > inconditionnaly 500ms this can ends up with the system time > being one second away from the wall clock time which NTP will take quite > some time to remove. I can't remember the details, but this was not the intention. As long as systohc and hctosys exist then the design goal of rtclib should be to provide sub-second accuracy on the round trip of time through the RTC. Otherwise what is the point? Jason