[U-Boot-Users] prob. faced in UBoot with 64MB SDRAM

Jerry Van Baren gerald.vanbaren at smiths-aerospace.com
Tue Apr 10 14:42:19 CEST 2007

Nethra wrote:
> Hello,
> I m using U-Boot 1.1.2 for custom board similar to MPC8272ADS board.
> On board it has 64MB Micron SDRAm and 16MB AMD flash.
> When Uboot is configured for 16MB SDRAM it works fine.
> A)But the same Uboot after doing necessary changes in OR1 to configure it
> for 64MB SDRAM.it fails to comeup properly.
> So for 16MB 
> OR1:0xFF0030C0
> for 64MB
> OR1:0xFC002CC0
> and other SDRAM register value remain the same 
> BR1                   0x00001841
> PSDMR               0x8266B73E
> PSRT                0x4B
> MPTPR               0x1300
> when we debugged the Uboot through BDI we found that it always hangs after
> relocating the code in SDRAM.
>  but we ar not sure what could be the reason.....
> B) Also we found that same uboot for second board with same SDRAM and FLASH
> it comes up properly.
> And after configuring boot arguements environment variables.It will download
> the kermel image 
> and after uncompressing kernel image and mount NFS properly.
> But when the root prompt comes board will get reset and again start
> executing uboot. 
> and this get repeated in a loop.
> C) One more observation on the second board where uboot comes up properly
> and kernel +Ramdisk boot arguments are configured.
> both kernel +Ramdisk image will be copied from tftp and start executing
> properly without any problem.
> As far as HW is concerned both the board is same w.r.t to components
> mounted.             
> kindly help in this respect with possible solution.
> Thanking you.

Hi Nethra,

Your SDRAM initialization sequence (PSDMR & friends) is most likely 
wrong for the new RAM devices.  What worked with the 16MB SDRAM is not 
going to work with the 64MB SDRAM, timing parameters are nearly 100% 
guaranteed to be different.

Best regards,

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