Row hammer refresh command
A memory controller issues a targeted refresh command. A specific row of a memory device can be the target of repeated accesses. When the row is accessed repeatedly within a time threshold (also referred to as “hammered” or a “row hammer event”), physically adjacent row (a “victim” row) may experience data corruption. The memory controller receives an indication of a row hammer event, identifies the row associated with the row hammer event, and sends one or more commands to the memory device to cause the memory device to perform a targeted refresh that will refresh the victim row.
1. A system comprising:
a synchronous dynamic random access memory (SDRAM) device, the SDRAM device including:
a memory array to include one or more rows of memory cells;
a mode register to hold at least one mode register bit, the value of the at least one mode register bit to determine whether a targeted row refresh mode is enabled; and
targeted row refresh logic coupled with the memory array, the targeted row refresh logic capable of refreshing selected rows responsive, at least in part, to a targeted row refresh command, the refreshing selected rows performed as a targeted row refresh having a refresh time (tRF) that is shorter than a refresh cycle time (tRFC) for the row; and
a memory controller coupled with the SDRAM device, the memory controller including detection logic to detect a targeted row refresh condition; and
command and control logic capable to issue a command to set the at least one mode register bit to transition the SDRAM device to the targeted row refresh mode, subsequent to detection of the targeted row refresh condition.
2. The system of claim 1 , wherein the command to transition the SDRAM device to a targeted row refresh mode includes a Mode Register Set (MRS) command.
3. The system of claim 2 , wherein the MRS command is an MRS 2 command.
4. The system of claim 3 , wherein the MRS 2 command sets an MR 2 [A 13 ] register to one.
5. The system of claim 2 , wherein the command to transition the SDRAM device to a targeted row refresh mode includes at least one Activate (ACT) command.
6. The system of claim 5 , wherein the ACT command is an ACT 1 command.
7. The system of claim 1 , wherein the SDRAM device is a DDR4 SDRAM device.
8. The system of claim 1 , wherein the SDRAM device is a LPDDR4 SDRAM device.
9. A synchronous dynamic random access memory (SDRAM) device, the SDRAM device comprising:
a memory army to include one or more rows of memory cells;
a mode register to hold at least one mode register bit, the value of the at least one mode register bit to determine whether a targeted row refresh mode is enabled; and
targeted row refresh logic coupled with the memory array, the targeted row refresh logic capable to refresh selected rows responsive, at least in part, to a targeted row refresh command, the refresh of selected rows performed as a targeted row refresh having a refresh time (tRF) that is shorted than a refresh cycle time (tRFC) for the row.
10. The SDRAM device of claim 9 , wherein the SDRAM device is a DDR4 SDRAM device.
11. The SDRAM device of claim 10 , wherein the SDRAM device is a LPDDR4 SDRAM device.
12. A memory controller comprising:
a double data rate (DDR) interface to couple the memory controller to a DDR memory channel;
detection logic to detect a targeted row refresh condition; and
command and control logic capable to issue a command to transition a synchronous dynamic random access memory (SDRAM) device to a targeted row refresh mode, subsequent to detection of the targeted row refresh condition, to enable the SDRAM to perform a targeted row refresh having a refresh time (tRF) that is shorter than a refresh cycle time (tRFC) for the row.
13. The memory controller of claim 12 , wherein the memory controller is integrated onto the same integrated circuit as a processor.
14. The memory controller of claim 12 , wherein the SDRAM device is a DDR4 SDRAM device.
15. The memory controller of claim 12 , wherein the SDRAM device is a LPDDR4 SDRAM device.