[rtc-linux] Re: [PATCH] rtc: pcf8523: refuse to write dates later than 2099

[Alexandre Belloni <alexandre.belloni@free-electrons.com>]

Hi,

On 06/11/2015 at 17:37:56 +0100, Uwe Kleine-K=C3=B6nig wrote :
> When the chip increments the YEAR register and it already holds
> bin2bcd(99) it reads as 0 afterwards. With this behaviour the last valid
> day (without trickery) that has a representation is 2099-12-31 23:59:59.
> So refuse to write later dates.
>=20
> Signed-off-by: Uwe Kleine-K=C3=B6nig <u.kleine-koenig@pengutronix.de>
> ---
> Hello,
>=20
> When setting the YEAR register to bin2bcd(100) =3D=3D 0xa0 it increments
> just fine up to bin2bcd(159) =3D=3D 0xf9 but these values are forbidden i=
n
> the manual. But this doesn't help to expand (or shift) the range of
> supported dates.
>=20
> An alternative to this patch would be to save tm_year % 100 because
> that's what happens when waiting long enough anyhow. Would that be
> better? Do we already care at all for year-2100-problems?
>=20

There is no way to tell whether the date is fine after February
2100 so I will take the patch as is.

--=20
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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