LPDDR4 memories use frequency set points to allow the memory to easily switch between two different frequencies without ever being in an un-trained state. There are two frequency set points - frequency set point 0 and frequency set point 1.
FSP is controlled through the following bits:
- DDRSS_CTL_192[0] DFS_ALWAYS_WRITE_FSP
- DDRSS_CTL_163[16] DISABLE_UPDATE_TVRCG
- DDRSS_CTL_192[16] FSP_OP_CURRENT
- DDRSS_CTL_191[24] FSP_PHY_UPDATE_MRW
- DDRSS_CTL_192[8] FSP_STATUS
- DDRSS_CTL_192[24] FSP_WR_CURRENT
- DDRSS_CTL_193[17-16] FSP0_FRC
- DDRSS_CTL_193[25-24] FSP1_FRC
- DDRSS_CTL_190[8] MR_FSP_DATA_VALID_F0
- DDRSS_CTL_190[16] MR_FSP_DATA_VALID_F1
- DDRSS_CTL_190[24] MR_FSP_DATA_VALID_F2
- DDRSS_CTL_166[4-0] TCKFSPE_F0
- DDRSS_CTL_168[4-0] TCKFSPE_F1
- DDRSS_CTL_171[4-0] TCKFSPE_F2
- DDRSS_CTL_166[12-8] TCKFSPX_F0
- DDRSS_CTL_168[28-24] TCKFSPX_F1
- DDRSS_CTL_171[12-8] TCKFSPX_F2
- DDRSS_CTL_166[31-16] TVREF_LONG_F0
- DDRSS_CTL_169[15-0] TVREF_LONG_F1
- DDRSS_CTL_171[31-16] TVREF_LONG_FN