Thanks @rock and @roy. I finally figured it out.
I double checked my HLS design. They had the same register space for control/data registers. But it still failed in running read/write any one of the registers after partial reconfiguration.
The issue is that Vivado’s automation (on validating) forced the CONFIG.NUM_READ_OUTSTANDING/NUM_WRITE_OUTSTANDING to be 8 to the HLS design, which was 1 on the design and might not be compatible for this simple design.
And it’s happening even without the decoupler whenever there is only one Master interface to the AXI Interconnect.
I’m sure it’s successfully partially reconfigured via adding additional gpio design output to the led pin to my original PR and seeing the led light changed, then the followup read/write transaction still hanged.
Adding other designs or following roy’s solution, that enables multiple Master interfaces on the AXI Interconnect, which prevents the CONFIG from forced 8, solves my issue.