Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752103AbdFTNsc (ORCPT ); Tue, 20 Jun 2017 09:48:32 -0400 Received: from mail.free-electrons.com ([62.4.15.54]:53303 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751060AbdFTNsa (ORCPT ); Tue, 20 Jun 2017 09:48:30 -0400 Date: Tue, 20 Jun 2017 15:48:27 +0200 From: Alexandre Belloni To: Pavel Machek Cc: Steve Twiss , Benjamin Gaignard , "linaro-kernel@lists.linaro.org" , "adi-buildroot-devel@lists.sourceforge.net" , Alessandro Zummo , Gregory Clement , Ingo Molnar , Jason Cooper , John Stultz , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Linus Walleij , Michael Chan , "netdev@vger.kernel.org" , "rtc-linux@googlegroups.com" , Sebastian Hesselbarth , Support Opensource , Thomas Gleixner , "x86@kernel.org" , Baruch Siach , Hans Ulli Kroll , Vladimir Zapolskiy , Sylvain Lemieux , Barry Song , Maxime Ripard , Chen-Yu Tsai , Thierry Reding , Jonathan Hunter , "linux-tegra@vger.kernel.org" , "patches@opensource.wolfsonmicro.com" , "Rafael J. Wysocki" , Len Brown , "linux-pm@vger.kernel.org" Subject: Re: [PATCH 00/51] rtc: stop using rtc deprecated functions Message-ID: <20170620134827.ubvzhh25klaotupv@piout.net> References: <1497951359-13334-1-git-send-email-benjamin.gaignard@linaro.org> <20170620100348.zh4ygvjjgnhxvmvl@piout.net> <20170620121011.GA13221@amd> <20170620122400.sm7qqvwyj6cuzarw@piout.net> <20170620132620.GA16881@amd> <6ED8E3B22081A4459DAC7699F3695FB7018CD96FCD@SW-EX-MBX02.diasemi.com> <20170620134458.GA10104@amd> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170620134458.GA10104@amd> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1950 Lines: 49 On 20/06/2017 at 15:44:58 +0200, Pavel Machek wrote: > On Tue 2017-06-20 13:37:22, Steve Twiss wrote: > > Hi Pavel, > > > > On 20 June 2017 14:26, Pavel Machek wrote: > > > > > Subject: Re: [PATCH 00/51] rtc: stop using rtc deprecated functions > > > > > > On Tue 2017-06-20 14:24:00, Alexandre Belloni wrote: > > > > On 20/06/2017 at 14:10:11 +0200, Pavel Machek wrote: > > > > > On Tue 2017-06-20 12:03:48, Alexandre Belloni wrote: > > > > > > On 20/06/2017 at 11:35:08 +0200, Benjamin Gaignard wrote: > > > > > > > rtc_time_to_tm() and rtc_tm_to_time() are deprecated because they > > > > > > > rely on 32bits variables and that will make rtc break in y2038/2016. > > > > > > > > > > > > Please don't, because this hide the fact that the hardware will not > > > > > > handle dates in y2038 anyway and as pointed by Russell a few month ago, > > > > > > rtc_time_to_tm will be able to catch it but the 64 bit version will > > > > > > silently ignore it. > > > > > > > > > > Reference? Because rtc on PCs stores date in binary coded decimal, so > > > > > it is likely to break in 2100, not 2038... > > > > > > > > I'm not saying it should be done but clearly, that is not the correct > > > > thing to do for RTCs that are using a single 32 bits register to store > > > > the time. > > > > You give one example, I can give you three: armada38x, at91sam9, > > > > at32ap700x and that just in the beginning of the series. > > > > > > I wanted reference to Russell's mail. > > > > This is it. > > https://patchwork.kernel.org/patch/6219401/ > > Thanks. > > Yes, that's argument against changing rtc _drivers_ for hardware that > can not do better than 32bit. For generic code (such as 44/51 sysfs, > 51/51 suspend test), the change still makes sense. > Yes, we agree on that but I won't cherry pick working patches from a 51 patches series. -- Alexandre Belloni, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com