linux-kernel - Re: [PATCH v3 3/4] rtc: isl1208: add support for isl1219 with tamper detection

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Message-ID: <20180308120549.GG20370@piout.net>
Date:   Thu, 8 Mar 2018 13:05:49 +0100
From:   Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:     Denis OSTERLAND <denis.osterland@...hl.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mgr@...gutronix.de" <mgr@...gutronix.de>,
        "m.grzeschik@...gutronix.de" <m.grzeschik@...gutronix.de>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "a.zummo@...ertech.it" <a.zummo@...ertech.it>,
        "linux@...ck-us.net" <linux@...ck-us.net>,
        "jdelvare@...e.com" <jdelvare@...e.com>,
        "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>
Subject: Re: [PATCH v3 3/4] rtc: isl1208: add support for isl1219 with tamper
 detection

On 08/03/2018 at 11:53:09 +0000, Denis OSTERLAND wrote:
> Am Mittwoch, den 07.03.2018, 11:47 +0100 schrieb Alexandre Belloni:
> > > > > +
> > > > > +	tv64.tv_sec = rtc_tm_to_time64(&tm);
> > > > Why not using an unsigned long long directly here? time64_t is not the
> > > > correct type.
> > > Do you mean timespec64 is not the correct type here?
> > > Then yes, sould be time64_t.
> > > If you mean time64_t is not the correct type here,
> > > then can you give me some detail why there is no rtc_tm_to_u64,
> > > or something like that?
> > The rtc subsystem forbids negative times, the proper type should be
> > unsigned.
> I will add rtc_vaild_tm check.
> 
> Which sequence for time conversion would you expect?
> 
> time64_t secs = rtc_tm_to_time64(&tm);
> BUG_ON(secs < 0);
> return sprintf(buf, "%llu\n", (unsigned long long)secs);
> 
> or
> 
> return sprintf(buf, "%llu\n", (unsigned long long)rtc_tm_to_time64(&tm));

rtc_vaild_tm will already return EINVAL in case of negative time so this
is the one you should use.

-- 
Alexandre Belloni, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com