thanks for the support, it helped to detect mmc1 uSD card .
but we have observed following issues
1. if usd card present before power on RPi, the Rpi is not booting , i guess the boot sequence has affected , how to fix boot this ?
2. the system hangs within few seconds of connecting uSD card
could you help us in fixing?
fryi: the image used is https://www.raspberrypi.org/downloads/raspbian/
: raspian buster lite