Thread (29 messages) 29 messages, 8 authors, 2017-06-21

[PATCH 00/51] rtc: stop using rtc deprecated functions

From: Pavel Machek <hidden>
Date: 2017-06-20 13:45:06
Also in: linux-pm, linux-rtc, linux-tegra, lkml, netdev

On Tue 2017-06-20 13:37:22, Steve Twiss wrote:
Hi Pavel,

On 20 June 2017 14:26, Pavel Machek wrote:
quoted
Subject: Re: [PATCH 00/51] rtc: stop using rtc deprecated functions

On Tue 2017-06-20 14:24:00, Alexandre Belloni wrote:
quoted
On 20/06/2017 at 14:10:11 +0200, Pavel Machek wrote:
quoted
On Tue 2017-06-20 12:03:48, Alexandre Belloni wrote:
quoted
On 20/06/2017 at 11:35:08 +0200, Benjamin Gaignard wrote:
quoted
rtc_time_to_tm() and rtc_tm_to_time() are deprecated because they
rely on 32bits variables and that will make rtc break in y2038/2016.
Please don't, because this hide the fact that the hardware will not
handle dates in y2038 anyway and as pointed by Russell a few month ago,
rtc_time_to_tm will be able to catch it but the 64 bit version will
silently ignore it.
Reference? Because rtc on PCs stores date in binary coded decimal, so
it is likely to break in 2100, not 2038...
I'm not saying it should be done but clearly, that is not the correct
thing to do for RTCs that are using a single 32 bits register to store
the time.
You give one example, I can give you three: armada38x, at91sam9,
at32ap700x and that just in the beginning of the series.
I wanted reference to Russell's mail.
This is it.
https://patchwork.kernel.org/patch/6219401/
Thanks.

Yes, that's argument against changing rtc _drivers_ for hardware that
can not do better than 32bit. For generic code (such as 44/51 sysfs,
51/51 suspend test), the change still makes sense.

								Pavel

-- (english)
http://www.livejournal.com/~pavelmachek (cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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