Link demo: https://www.youtube.com/watch?v=w6fq1kdeElY
All in one images:
Step 1: open Hyperlink of a field in main report
Step 2: Select Link Target = Self ; Slect Link Type = ReportExecution
Step 3: Find on Target Report (DrillDown Report) two main input-parameters to open the report via link from main report. (in my case the drilldown report just need one parameter (requestID) and the Path will be got from Properties popup window of target report.
Now you can cook your linking report (main report) with all what I show here: