How to check pmi unity matrix?

Hi Experts.

For checking if I have pmi unity matrix 4x4 or not unity matrix, what UE shall report in case of unity pmi matrix?
pmi index 1?
Configuring 4x4 mimo layers and UE reports ri 4 with bum of layers 4 so what shall be pmi index (i.e. unity matrix index)?

UE never reports PMI matrix.
It reports some indices i11 i12 i13 and i21, check sharetechnote page for this.
So it does not report a matrix but some indices.

Yes, UE reports x1 x2 for pmi.

What are pmi i1 i2 i3 i21 shall be in case of unity matrix 4x4?