Control register for DMC features.
The feature_control_now register characteristics are:
- Usage constraints
Can be read from when in ALL states. Cannot be written to and only updated when in CONFIG, LOW-POWER or PAUSED states.
There is only one DMC configuration.
The following figure shows the bit assignments.
Figure 3-268 feature_control_now register bit assignments
The following shows the bit assignments.
- [31:29] Reserved_3
-  alert_mode_now
Configures the DMC behavior in response to dfi_alert_n being asserted.
NoteWhen performing DIMM CA training using the ALERT pin this mode must be
set to interrupt-only mode.
- [27:20] address_mirroring_mask_now
Each bit determines if address mirroring as per the DDR3/DDR4 RDIMM Design Specification must be applied to the corresponding rank. Set to 1 to enable mirroring, 0 to disable. Normally, this bit must be set high for odd physical ranks.
-  dfi_err_mode_now
Configures the DMC behavior in response to dfi_err being asserted.
-  lvl_wakeup_en_now
Program to enable the DMC to bring a rank out of self-refresh to perform PHY training. This must not be enabled when using geardown mode.
-  mrs_output_inversion_now
Program to enable output inversion for MRS commands for DDR4 DIMMs.
-  address_mirroring_now
Program to enable address mirroring for ranks identified by address_mirroring_mask.
-  trr_enable_now
Program to enable issue of Target Row Refresh command on detection of potential maximum activate count (tMAC) violation. Must only be enabled for memories supporting this command.
-  Reserved_2
-  temp_poll_after_xsref_now
Program to insert an automatic temperature status poll command following exit from self-refresh.
- [12:9] temp_poll_after_n_ref_now
Program to insert an automatic temperature status poll command following issue of n AUTOREFRESH commands. 0 disables the functionality. 1 is RESERVED
-  zqcs_after_xsref_now
Program to insert an automatic ZQC short calibration command following exit from self-refresh.
- [7:4] zqcs_after_n_ref_now
Program to insert an automatic ZQC short calibration command following n refreshes. 0 - disables the functionality. 1 is RESERVED
-  two_t_timing_now
Program to enable or disable 2T command timing.
-  Reserved_1
-  crc_enable_now
Program to enable or disable Cyclic Redundancy Check (CRC) functionality on
NoteWhen you enable CRC, the parameters t_wr,
t_wtr and t_wtw must be extended by one cycle to
accommodate the CRC functionality.
-  write_dbi_enable_now
Program to enable or disable Data Bus Inversion (DBI) functionality for writes.