[U-Boot] [ppc440epx : memory extention]

[Stefan Roese <sr@denx.de>]

On Tuesday 16 September 2008, sean wrote:
> I'd like to extend capacity of DDR2 memory from 256MB to 512MB on my
> custumn board.

So you have a custom board port for your specific board, correct? Is the DDR2 
hardware design similar to the one on Sequoia? What are the differences here?

> EV Board(SEQUOIA) has 256MB DDR2 memory.
>
>
>
> When I reset the U-Boot program, U-boot show me the SDRAM test fail message
> like below.
>
>
>
> DRAM: 512MB
>
> SDRAM test fails at : 00000000
>
>
>
> What should I do to upgrade DDR2 memory??
>
> I have only modified follow sessions of U-Boot Code. Is it right??
>
> 1)     Sequoia.h
>
> #define CFG_MBYTES_SDRAM        (512)

Yes.

> 2)     Sdram.c
>
>            /* For 512M DDR Registers */
>
>            mtsdram(DDR0_02, 0x00000000);

<snip>

Can't comment here. This is really complex and pretty board/DDR2 specific.

> And should I modify on table entry(in init.s)
>
> tlbentry( CFG_SDRAM_BASE, SZ_256M, CFG_SDRAM_BASE, 0, AC_R|AC_W|AC_X|SA_G)

Yes, you need to add another TLB entry for the 2nd 256MB. Or you could remove 
those entries completely and use program_tlb() to add the TLB(s).

Best regards,
Stefan

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