Date: Thu, 8 Jun 2017 17:05:40 +0200
From: Alexandre Belloni <alexandre.belloni@free-electrons.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Rasmus Villemoes <rasmus.villemoes@prevas.dk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Alessandro Zummo <a.zummo@towertech.it>, linux-rtc@vger.kernel.org,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Guan Xuetao <gxt@mprc.pku.edu.cn>, Ingo Molnar <mingo@kernel.org>,
        Jason Wessel <jason.wessel@windriver.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Thierry Reding <thierry.reding@gmail.com>
Subject: Re: [PATCH v1 04/25] lib/vsprintf: Print time and date in human
 readable format via %pt
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On 08/06/2017 at 17:55:12 +0300, Andy Shevchenko wrote:
> On Thu, Jun 8, 2017 at 5:49 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> > On Thu, Jun 8, 2017 at 3:47 PM, Andy Shevchenko
> > <andriy.shevchenko@linux.intel.com> wrote:
> >> There are users which print time and date represented by content of
> >> struct rtc_time in human readable format.
> >>
> >> Instead of open coding that each time introduce %pt[dt][rv] specifier.
> >
> > I really like the idea, and the implementation seems fine for this use case, but
> > before we reserve %pt for rtc_time, could we discuss whether we want
> > that for printing struct tm, struct timespec64, time64_t or ktime_t instead?
> 
> How many users? For struct tm it's somelike 4 (which want to print its content).
> 
> > I can see good reasons for pretty-printing any of them, but the namespace for
> > format strings is rather limited.
> >
> > struct rtc_time is almost the same as struct tm (the former has one extra
> > member), so maybe we can actually define them to be the same and
> > use one format string for both?
> 
> The reason I decide to drop struct tm for now due to they are not
> compatible and I have got an interesting bugs.
> Verify tm_year member carefully.
> 

I understand this may not fit your debugging needs but what about pretty
printing time64_t and using rtc_tm_to_time64?


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