Hello Mandeep! 

First of all GDPI is not the first step in the admission process. You must take the entrance exams such as CLAT, AILET,LSAT. After which on the basis of the rank you get you can take the admission. 

And yes there is GDPI round, but only in some colleges not in all colleges. But it will be afterwards so first you have to give entrance exam for admission in five year law course. 

Thankyou. All the best!