AM5728: How to detect a SATA fault

Part Number: AM5728

Tool/software:

I would like to determine the behavior of the SATA driver when the error bit in the following register is set.
What operation or external factor sets this bit?

SATA_PxSERR
  bit26 DIAG_X
  bit25 DIAG_F
  bit24 DIAG_T
  bit23 DIAG_S
  bit22 DIAG_H
  bit21 DIAG_C
  bit19 DIAG_B
  bit18 DIAG_W
  bit16 DIAG_N
  bit11 ERR_E
  bit10 ERR_P
  bit9 ERR_C
  bit8 ERR_T
  bit1 ERR_M
  bit0 ERR_I