linux-kernel - Re: [PATCH 2/4] rtc: s3c: Add time range

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Message-ID: <YW8EfIFolQ2SmBHt@piout.net>
Date:   Tue, 19 Oct 2021 19:46:36 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Sam Protsenko <semen.protsenko@...aro.org>
Cc:     Alessandro Zummo <a.zummo@...ertech.it>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        linux-rtc@...r.kernel.org,
        Linux Samsung SOC <linux-samsung-soc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/4] rtc: s3c: Add time range

On 19/10/2021 19:31:55+0300, Sam Protsenko wrote:
> On Tue, 19 Oct 2021 at 19:20, Alexandre Belloni
> <alexandre.belloni@...tlin.com> wrote:
> >
> > On 19/10/2021 16:17:22+0300, Sam Protsenko wrote:
> > > This RTC driver only accepts dates from 2000 to 2099 year. It starts
> > > counting from 2000 to avoid Y2K problem, and S3C RTC only supports 100
> > > years range. Provide this info to RTC framework.
> > >
> > > Signed-off-by: Sam Protsenko <semen.protsenko@...aro.org>
> > > ---
> > >  drivers/rtc/rtc-s3c.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > >
> > > diff --git a/drivers/rtc/rtc-s3c.c b/drivers/rtc/rtc-s3c.c
> > > index 10e591794276..d9994efd70ef 100644
> > > --- a/drivers/rtc/rtc-s3c.c
> > > +++ b/drivers/rtc/rtc-s3c.c
> > > @@ -454,6 +454,8 @@ static int s3c_rtc_probe(struct platform_device *pdev)
> > >       }
> > >
> > >       info->rtc->ops = &s3c_rtcops;
> > > +     info->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
> > > +     info->rtc->range_max = RTC_TIMESTAMP_END_2099;
> > >
> >
> > This change is missing the if (year < 0 || year >= 100)  removal in
> > s3c_rtc_settime()
> >
> 
> It's not actually removed in [PATCH 3/4] (if I'm following you
> correctly), it was replaced with this code:
> 
> <<<<<<<<<<<<<<<<<<<<<<< cut here >>>>>>>>>>>>>>>>>>>
>     if (rtc_tm.tm_year < 0 || rtc_tm.tm_year >= 100) {
>         dev_err(dev, "rtc only supports 100 years\n");
>         return -EINVAL;
>     }
> <<<<<<<<<<<<<<<<<<<<<<< cut here >>>>>>>>>>>>>>>>>>>
> 

After setting the range, the core will never pass values outside of this
range so it is not necessary to check in the driver anymore.

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com