On 17/07/2019 16:54:54+0800, Ran Bi wrote: > > > + > > > +/* we map HW YEAR 0 to 1968 not 1970 because 2000 is the leap year */ > > > +#define RTC_MIN_YEAR 1968 > > > +#define RTC_BASE_YEAR 1900 > > > +#define RTC_MIN_YEAR_OFFSET (RTC_MIN_YEAR - RTC_BASE_YEAR) > > > > Do not do that. If this RTC range starts in 200, ths is what the driver > > has to support, you should not care about dates before 2000. Note that > > the RTC core can still properly shift the range if it is absolutely > > necessary. > > > > Do we need to care about default alarm date 1970-01-01? Or can I just > set it to 2000-01-01? >
You never have to set a default value. It doesn't add any value versus an unknown value. > > > + > > > +static inline u32 rtc_readl(struct mt2712_rtc *rtc, u32 reg) > > > > Please use a more descriptive prefix than just rtc_. > > > > Do you mean it's better to use prefix "mt2712_rtc_"? > Yes. > > > + > > > + /* > > > + * register status was not correct, > > > + * need set time and alarm to default > > > + */ > > > + if (p1 != RTC_POWERKEY1_KEY || p2 != RTC_POWERKEY2_KEY > > > + || !valid_rtc_time(rtc)) { > > > + reset_rtc_time(rtc); > > > > Do not do that. This is valuable information. If the time is invalid, > > report it as such in read_time and read_alarm. Resetting the time here > > will lead to more issues later (i.e. userspace is not able to know > > whether the time is set correctly or not). > > > > When RTC's power run out, RTC will lost it's registers value and time > data at next boot up. We even cannot know what the date and time it > shows. We want to check this state here and set a default RTC date. Do > you think it's no need here and the date should be set by system? > If I understand correctly, the POWERKEY register will lose their value. This means that you know that the time is incorrect. instead of setting it to a default value and losing that valuable information, simply check for that in read_time and return EINVAL in that case. then on the next set_time invocation, you can set the POWERKEY registers and set the time to a known value. -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com