it seems rtc1 rules worked
root@tegra-ubuntu:/home/ubuntu# ls -la /dev/rtc
lrwxrwxrwx 1 root root 4 Jan 1 00:00 /dev/rtc -> rtc1
and output of hwclock -r is correct
root@tegra-ubuntu:/home/ubuntu# hwclock -r
Wed 29 Jan 2020 11:17:59 AM UTC -0.429637 seconds
but i still have problem !!!
Sat Jan 1 00:03:21 UTC 2000
it seems system time still not correct . perhaps i should run hwclock -s at the beginning as an autostart program , is it true?
excuse me for lot of my stupid questions perhaps it is better to block my ID in toradex community