Re: RTC issue
I have seen the same message on an i.MX6S7 (https://www.karo-electronics.com/fileadmin/download/Datasheets/TX6S-Datasheet.pdf) with kernel 5.10 (in a dunfell Yocto after I upgraded from kernel 4.14).
Since we use an external RTC on the I2C bus, I disabled the internal RTC ("snvs_rtc") in the device tree, and did not analyze the problem further.
I think it is a kernel problem, since in my case the Yocto version has not changed.
Please inform me if you find out something.