Re: [PATCH v3 4/5] rtc: mt6397: Remove start time parameters

[AngeloGioacchino Del Regno]

Il 11/04/25 15:39, Alexandre Belloni ha scritto:
> On 11/04/2025 15:36:12+0200, Alexandre Belloni wrote:
> > On 11/04/2025 14:35:57+0200, Alexandre Mergnat wrote:
> > > The start time parameters is currently hardcoded to the driver, but
> > > it may not fit with all equivalent RTC that driver is able to support.
> > >
> > > Remove the start_secs and set_start_time value setup because it
> > > will be handled by the rtc_device_get_offset function using the
> > > start-year DTS property.
> > >
> > > Signed-off-by: Alexandre Mergnat <amergnat@xxxxxxxxxxxx>
> > > ---
> > >   drivers/rtc/rtc-mt6397.c | 2 --
> > >   1 file changed, 2 deletions(-)
> > >
> > > diff --git a/drivers/rtc/rtc-mt6397.c b/drivers/rtc/rtc-mt6397.c
> > > index 692c00ff544b2..d47626d47602f 100644
> > > --- a/drivers/rtc/rtc-mt6397.c
> > > +++ b/drivers/rtc/rtc-mt6397.c
> > > @@ -291,8 +291,6 @@ static int mtk_rtc_probe(struct platform_device *pdev)
> > >   	rtc->rtc_dev->ops = &mtk_rtc_ops;
> > >   	rtc->rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_1900;
> > >   	rtc->rtc_dev->range_max = mktime64(2027, 12, 31, 23, 59, 59);
> > > -	rtc->rtc_dev->start_secs = mktime64(1968, 1, 2, 0, 0, 0);
> > > -	rtc->rtc_dev->set_start_time = true;
> > >   
> >
> > This is going to break the time for people upgrading their kernel, you
> > are unfortunately stuck with this.
>
> To be clear, the breakage will happen when upgrading the kernel but not
> the device tree with 5/5

Yes, you're stuck with this. Devicetree has to be retrocompatible.

Besides, this start_secs is what gets used by default, and the start-year
devicetree property should take precedence and effectively override the
start_secs default.

Just keep it there.... :-)

Cheers,
Angelo

> > >   	return devm_rtc_register_device(rtc->rtc_dev);
> > >   }
> > >
> > > --
> > > 2.25.1
> >
> > --
> > Alexandre Belloni, co-owner and COO, Bootlin
> > Embedded Linux and Kernel engineering
> > https://bootlin.com