linux-kernel - Re: [PATCH 00/51] rtc: stop using rtc deprecated functions

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Message-ID: <20170621094146.ebq5hxuvtmfdgekz@piout.net>
Date:   Wed, 21 Jun 2017 11:41:46 +0200
From:   Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:     Russell King - ARM Linux <linux@...linux.org.uk>
Cc:     Pavel Machek <pavel@....cz>, Thomas Gleixner <tglx@...utronix.de>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Baruch Siach <baruch@...s.co.il>,
        "patches@...nsource.wolfsonmicro.com" 
        <patches@...nsource.wolfsonmicro.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        "x86@...nel.org" <x86@...nel.org>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Chen-Yu Tsai <wens@...e.org>, Ingo Molnar <mingo@...hat.com>,
        Sylvain Lemieux <slemieux.tyco@...il.com>,
        Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
        Len Brown <len.brown@...el.com>,
        "linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>,
        Jason Cooper <jason@...edaemon.net>,
        "rtc-linux@...glegroups.com" <rtc-linux@...glegroups.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        Hans Ulli Kroll <ulli.kroll@...glemail.com>,
        "adi-buildroot-devel@...ts.sourceforge.net" 
        <adi-buildroot-devel@...ts.sourceforge.net>,
        Vladimir Zapolskiy <vz@...ia.com>,
        John Stultz <john.stultz@...aro.org>,
        Gregory Clement <gregory.clement@...e-electrons.com>,
        Michael Chan <michael.chan@...adcom.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Barry Song <baohua@...nel.org>,
        Support Opensource <Support.Opensource@...semi.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Steve Twiss <stwiss.opensource@...semi.com>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>
Subject: Re: [PATCH 00/51] rtc: stop using rtc deprecated functions

On 21/06/2017 at 10:19:49 +0100, Russell King - ARM Linux wrote:
> On Wed, Jun 21, 2017 at 10:39:07AM +0200, Alexandre Belloni wrote:
> > On 21/06/2017 at 09:51:52 +0200, Pavel Machek wrote:
> > > If someone uses different threshold, well, there will be
> > > confusion. But only for users that have their rtc set to the past,
> > > which is quite unusual.
> > > 
> > 
> > Or not, having an RTC set in the past is actually quite common. I'd find
> > it weird to have a new device boot and be set to a date in the future.
> 
> ... and that basically means you can't use hardware that stores RTC
> time as a 32-bit number of seconds past 2106.
> 

And I guess it will not matter much for us anyway ;)

> > Also note that the threshold or offset thing may seem like a good idea
> > but fails with many RTCs because of how they handle leap years.
> 
> Not for the case being discussed.  A 32-bit counter of seconds knows
> nothing about leap years - all that is handled by the conversion
> functions.
> 

Well, the patch series touches some RTCs that are not using 32 bit
counter so I though I might as well raise the issue now.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com