Make sure that smallest matrix involved in a multiplication is not split and bring it to the same process grid as the other 2 matrices.
Type  Intent  Optional  Attributes  Name  

type(mp_comm_type),  intent(in)  ::  mp_comm 
communicator that defines Cartesian topology 

type(dbcsr_tas_type),  intent(inout)  ::  matrix_in  
type(dbcsr_tas_type),  intent(out)  ::  matrix_out  
logical,  intent(in)  ::  transposed 
Whether matrix_out should be transposed 

character(len=1),  intent(inout)  ::  trans 
update transpose flag for DBCSR mm according to 'transposed' argument 

logical,  intent(in),  optional  ::  nodata 
Data of matrix_in should not be copied to matrix_out memory optimization: move data such that matrix_in is empty on return. 

logical,  intent(in),  optional  ::  move_data 
Data of matrix_in should not be copied to matrix_out memory optimization: move data such that matrix_in is empty on return. 