Re: [PATCH v2 2/4] rtc: mediatek: add driver for RTC on MT7622 SoC

Alexandre Belloni
2017-10-18T12:57:47Z

On 18/10/2017 at 19:12:06 +0800, Yingjoe Chen wrote:
> On Tue, 2017-10-17 at 17:40 +0800, sean.wang@mediatek.com wrote:
> > From: Sean Wang <sean.wang@mediatek.com>
> >
> > This patch introduces the driver for the RTC on MT7622 SoC.
> >
> > Signed-off-by: Sean Wang <sean.wang@mediatek.com>
> > ---
> > drivers/rtc/Kconfig | 10 ++
> > drivers/rtc/Makefile | 1 +
> > drivers/rtc/rtc-mt7622.c | 418 +++++++++++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 429 insertions(+)
> > create mode 100644 drivers/rtc/rtc-mt7622.c
> >
> > diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> > index e0e58f3..4226295 100644
> > --- a/drivers/rtc/Kconfig
> > +++ b/drivers/rtc/Kconfig
> > @@ -1705,6 +1705,16 @@ config RTC_DRV_MOXART
> > This driver can also be built as a module. If so, the module
> > will be called rtc-moxart
> >
> > +config RTC_DRV_MEDIATEK
>
> How about changing this to RTC_DRV_MT7622 or RTC_DRV_MEDIATEK_SOC?
> It is confusing to have both RTC_DRV_MEDIATEK & RTC_DRV_MT6397 here.
>

Yes, this has to be RTC_DRV_MT7622. It doesn't matter if it support
future SoCs named differently, it will be less confusing than using
anything with only mediatek in it.

> > + return -EINVAL;
> > +
> > + /* Keep yr_base used to calculate the calculate year when userspace
> > + * queries and extend the maximum year the RTC can count.
> > + */
> > + hw->yr_base[MTK_TC] = tm->tm_year - MTK_RTC_TM_YR_L -
> > + (tm->tm_year % MTK_RTC_HW_YR_LIMIT);
>
>
> I'm not sure this worth it.
> If maximum year it can hold is 99, I'd bet it won't support leap year
> correctly after 2100. This make the RTC useless after that.
>
> Also, yr_base is lost after power cycle, so you can't get correct year
> back anyway.
>

I agree, the best you can do here is to only support 2000 to 2099.

--
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering