Hello,

I stumbled across the following possible off-by-one error in counting the month in RTC driver rv8803.

I'am using struct rtc_time to define a EOL date for my U-Boots. So after this date U-Boot stops booting by reading the RTC before with rtc_get(). I'am using the same EOL code for two different imx boards with different RTCs and therefore different RTC drivers. On both boards I have set the same EOL date.

So the EOL Date is 25.09.2022 23:59:59

The board with rv3029 stopps booting on 26.09.2022 0:00:00 The board with rv8803 stopps booting on 26.08.2022 0:00:00

U-Boot Code: (drivers/rtc/rv3029.c)

v3029_rtc_set() ... regs[RV3029_W_MONTHS - RV3029_W_SEC] = bin2bcd(tm->tm_mon + 1); ...

rv3029_rtc_get() ... tm->tm_mon = bcd2bin(regs[RV3029_W_MONTHS - RV3029_W_SEC]) - 1; ...

(drivers/rtc/rv8803.c) rv8803_rtc_set() ... buf[RTC_MON_REG_ADDR] = bin2bcd(tm->tm_mon) ...

rv8803_rtc_get() ... tm->tm_mon = bcd2bin(buf[RTC_MON_REG_ADDR] & 0x1F); ...

I assume that the error is here and increase and decrease by one is also required here like in the Linux driver code for RTC 8803.

Linux Code:

rv3029_set_time() ... regs[RV3029_W_MONTHS - RV3029_W_SEC] = bin2bcd(tm->tm_mon + 1); ...

rv3029_read_time() ... tm->tm_mon = bcd2bin(regs[RV3029_W_MONTHS - RV3029_W_SEC]) - 1; ...

rv8803_set_time() ... date[RV8803_MONTH] = bin2bcd(tm->tm_mon + 1); ...

rv8803_get_time() ... tm->tm_mon = bcd2bin(date[RV8803_MONTH] & 0x1f) - 1; ...

Can someone verify and comment on this. Then I would prepare a patch later on.

Best Regards,

Oliver