From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Lukasz Majewski <lukma@denx.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>,
linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rtc: Add support for century bits to m41t62 (rv4162) RTC devices
Date: Thu, 3 Oct 2019 14:35:38 +0200 [thread overview]
Message-ID: <20191003123538.GS4106@piout.net> (raw)
In-Reply-To: <20191003142150.3d73a9d7@jawa>
On 03/10/2019 14:21:50+0200, Lukasz Majewski wrote:
> >
> > See the datasheet:
> >
> > "During any year which is a multiple of 4, the RV-4162 RTC will
> > automatically insert leap day, February 29. Therefore, the
> > application software must correct for this during the exception years
> > (2100, 2200, etc.) as noted above."
>
> I'm wondering what the phrase "application software" means here?
>
> If it is the userland SW, then we shall at least be able to set 2099 in
> this device and then count on software correction.
>
> If the "application software" is the kernel driver - the date
> correction shall be done there (maybe some lookup table?).
>
> Personally, I do prefer the first option - this means that with this
> patch we can set the time to e.g. 2234 year and then rely on userland
> software (or libc) to do the correction.
>
It is not possible to ensure this correction is properly done in
software, there is no point in letting the user set those bits.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
next prev parent reply other threads:[~2019-10-03 12:35 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-11 15:48 [PATCH] rtc: Add support for century bits to m41t62 (rv4162) RTC devices Lukasz Majewski
2019-09-30 7:56 ` Lukasz Majewski
2019-10-03 11:48 ` Alexandre Belloni
2019-10-03 12:21 ` Lukasz Majewski
2019-10-03 12:35 ` Alexandre Belloni [this message]
2019-10-03 13:14 ` Lukasz Majewski
2019-10-03 13:43 ` Alexandre Belloni
2019-10-03 14:10 ` Lukasz Majewski
2019-10-03 14:23 ` Alexandre Belloni
2019-10-03 14:49 ` Lukasz Majewski
2019-10-03 21:34 ` Alexandre Belloni
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