
4/29/2020
Loongson 3A3000 / 3B3000 Processor User Manual
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Always low
The timing is shown below:
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Godson 3A3000 / 3B3000 Processor User Manual • Volume 1
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By cooperating with the latter two reset modes, it is possible to realize STR directly using the reset signal of the memory controller
control. When the entire system is started from a shutdown state, use the method in (2) to use the memory module to reset normally and start
jobs. When the system recovers from the STR, use the method in (3) to reconfigure the memory module so that it does not damage
The original state of the memory module makes it resume normal operation.
9.5.3
Leveling
Leveling operation is in DDR3, used to intelligently configure the phase relationship between various signals in the read and write operations of the memory controller
Operation. Usually it includes Write Leveling, Read Leveling and Gate Leveling. In this controller,
Only Write Leveling and Gate Leveling are implemented, Read Leveling is not implemented, the software needs to pass judgment
The correctness of reading and writing to achieve the functions completed by Read Leveling. In addition to the DQS phase operating during Leveling
In addition to the bit and GATE phase, the configuration of writing DQ phase and reading DQ phase can be calculated according to these last confirmed phases
Reset method.
9.5.3.1 Write Leveling
(1)
Write Leveling is used to configure the phase relationship between writing DQS and clock. Software programming needs to refer to
The next step.
(2) Complete the controller initialization, see the previous section;
(3) Set Dll_wrdqs_x (x = 0… 8) to 0;
(4) Set Lvl_mode (0x180) to 2'b01;
(5) Sampling the Lvl_ready (0x180) register, if it is 1, it means that the Write Leveling request can be started;
(6) Set Lvl_req (0x180) to 1;
(7) Sampling the Lvl_done (0x180) register, if it is 1, it means that a Write Leveling request is completed;