[U-Boot-Users] DDR SDRAM in DIMM module forYosemite-likePPC440EP board.

Leonid Leonid at a-k-a.net
Fri Oct 20 20:02:15 CEST 2006

On Friday, October 20, 2006 9:50 AM Ben Warren wrote:
> Of course you don't have to use the SPD stuff, but you should.  

[Leonid] Unfortunately SPD stuff is out of question - on our board
UDIMM's EEPROM is not connected to CPU I2C bus.

> If the
> BDI won't work as-is, you need to learn more about your DDR controller
> and your particular DIMM's timing information, both of which should be
> readily available.  While DDR control is fairly complicated, there
> aren't that many knobs to turn and you may get lucky early on.

[Leonid] That what I'm going to do. I have datasheet, the module name is
MT8VDDT12832U. If somebody from this community happens to have BDI or
u-boot configuration for such or similar module, I'll appreciate that

> Another approach that's less systematic is to get U-boot working, dump
> the DDR controller register contents and use those in your BDI config
> file.  

[Leonid] I'm familiar with this method - I used it to get BDI work with
some ARM board. Yet as you said I must have u-boot working with this
DIMM first and provided I don't have SPD option it will probably require
exactly the same effort as BDI configuration - configure all registers
properly manually.

> This will involve a few painful workspace-less flash burns,
> though...  You can save a bit of pain by stripping your U-boot image
> bare-bones.

[Leonid] It's not that bad actually - takes less than 2 minutes to burn
entire 512KB u-boot image together with flash erasing even without
workspace. But as I see now I may as well concentrate on BDI config file
- exactly same registers must be configured - without touching u-boot
code at all for the time being.

> Sorry there's no easier answer, but if your hardware is wired right
> you'll probably nail this quickly.

[Leonid] I do appreciate your help, thanks a lot.


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