Configuring DRAM register using SPD.

[sivakumar]

Hi,

I am using spd_82801.c file to get the SPD values of the my DDR SDRAM. I have checked the values and it seem to be correct.
Now I want to program the DRAM registers. When I was browsing the 440gx code, I could found that these SPD values are not used directly to
get the DRAM register value. 

I could not  understand the step used to calculate the DRAM register values. In the specification I could see only the description of DRAM register, not the 
steps to calculate the value of DRAM register. Where can I find those steps? How do you get to know for the 440gx ? Is it ok to hardcode the values ?
I am going for this option because our system is a embedded system, so the configuration will not change.

Also while browsing the 440gx code, I found that  most of the register are left with default values. Can any one giving some idea about the set of registers which I need to 
program. I have attached the output of the SPD program. But how to calculate the DRAM register values like DRB, DRT, DRC,FDHC and etc., 


The Output of the SPD_82801.c file on my DDR SDRAM:

[root at wipro2 scanspd]# ./spd_82801ba
dev=1f, fn=3
IO_BASE=5000
After reset status 0x40
SLOT 0
After reset status 0x40
Number of bytes used by module manufacturer 0x80
After reset status 0x40
Memory Type 0x07 ---------------> DDR SDRAM
After reset status 0x40
Number of Row Address bits 0x0d
After reset status 0x40
Number of Column Address bits 0x0a
After reset status 0x40
Number of Sides 0x01
After reset status 0x40
DIMM Configuratio type 0x00
After reset status 0x40
Refresh Rate 0x82-------------------------------> refresh rate is 7.8 micro sec
After reset status 0x40
Number of Banks 0xa0
After reset status 0x40
Module Bank Density 0x40
After reset status 0x40
SPD Revision Code 0x00
After reset status 0x40
CAS # Latency 0x0c               -----------------------> 2.5
After reset status 0x40
Min Row Precharge 0x50
After reset status 0x40
Min RAS to CAS Delay 0x50 ------------------------------> 20 ns
After reset status 0x40
Min RAS Pulse Width 0x2d
[root at wipro2 scanspd]#


Thanks,
Siva



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