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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sat, 11 Sep 2021 10:05:02 -0700
Message-ID: <CAHk-=wgPJrMhr1_62O2xwD1QbT9oxJJ_uXw2mm6sa0hNDrFuwQ@mail.gmail.com>
Subject: Re: [GIT PULL] RTC changes for 5.15
To:     Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc:     linux-rtc@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Sat, Sep 11, 2021 at 8:59 AM Alexandre Belloni
<alexandre.belloni@bootlin.com> wrote:
>
> The broken down time conversion is similar to what is done
> in the time subsystem since v5.14.

By "similar" you mean "identical", no?

Why is the rtc subsystem not just using the generic time64_to_tm()?

Yes, yes, I realize that due to historical mistakes, there's a
duplicate 'struct rtc_time' struct, but it turns out that that is
_identical_ to 'struct tm' except it also has a 'int tm_isdst' at the
end.

So you could literally make a union of the two, pass the 'struct tm'
part down to the generic code, and just do

     rtc_tm->tm_isdst = 0;

at the end.

Rather than have a duplicate copy of that admittedly clever Neri and
Schneider algorithm.

Hmm?

             Linus