Hi, Alexandre, On 17.06.2024 10:31, claudiu beznea wrote: > On 17.06.2024 10:25, Alexandre Belloni wrote: >> On 14/06/2024 14:06:38+0300, claudiu beznea wrote: >>>>> + /* >>>>> + * Stop the RTC and set to 12 hours mode and calendar count mode. >>>>> + * RCR2.START initial value is undefined so we need to stop here >>>>> + * all the time. >>>>> + */ >>>> Certainly not, if you stop the RTC on probe, you lose the time >>>> information, this must only be done when the RTC has never been >>>> initialised. The whole goal of the RTC is the keep time across reboots, >>>> its lifecycle is longer than the system. >>> This was also my first thought when I read the HW manual. >>> >>> It has been done like this to follow the HW manual. According to HW manual >>> [1], chapter 22.3.19 RTC Control Register 2 (RCR2), initial value of START >>> bit is undefined. >>> >>> If it's 1 while probing but it has never been initialized, we can falsely >>> detect that RTC is started and skip the rest of the initialization steps. >>> W/o initialization configuration, the RTC will not be able to work. >>> >>> Even with this implementation we don't loose the time b/w reboots. Here is >>> the output on my board [2]. The steps I did were the following: >>> 1/ remove the power to the board (I don't have a battery for RTC installed >>> at the moment) >>> 2/ boot the board and issue hwclock -w >>> 3/ reboot >>> 4/ check the systime and rtc time >>> 5/ poweroff >>> 6/ poweron >>> 7/ boot and check systime and RTC time >>> >>> As you can see the time is not lost but continue to increment. I presume >>> the hardware takes into account that time needs to increment when initial >>> configuration is executed. >> I don't think so, I guess it stops ticking but the registers are not >> reset so when ts starts ticking again, you are not too far from the time >> that it should report. > I'll double check with hardware team on this and return with an answer. It has been confirmed me that the HW manual has a mistake and we can avoid stopping the RTC here every time. I'll adjust it in the next version. Thank you, Claudiu Beznea
